39 research outputs found
Impact of content storage and retrieval mechanisms on the performance of vehicular delay-tolerant networks
“Copyright © [2010] IEEE. Reprinted from 18th International Conference on Software, Telecommunications and Computer Networks (SoftCOM 2010). ISBN: 978-1-4244-8663-2
. This material is posted here with permission of the IEEE. Internal or personal use of this material is permitted. However, permission to reprint/republish this material for advertising or promotional purposes or for creating new collective works for resale or redistribution must be obtained from the IEEE by writing to [email protected]. By choosing to view this document, you agree to all provisions of the copyright laws protecting it.”Vehicular Delay-Tolerant Networking (VDTN) is a new disruptive network architecture based on the concept of delay tolerant networks (DTNs). VDTNs handle non-real time applications using vehicles to carry messages on their buffers, relaying them only when a proper contact opportunity occurs. Therefore, the network performance is directly affected by the storage capacity and message retrieving of intermediate nodes. This paper proposes a suitable content storage and retrieval (CSR) mechanism for VDTN networks. This CSR solution adds additional information on control labels of the setup message associated to the corresponding data bundle (aggregated traffic) that defines and applies caching and forwarding restrictions on network traffic (data bundles). Furthermore, this work presents a performance analysis and evaluation of CSR mechanisms over a VDTN application scenario, using a VDTN testbed. This work presents the comparison of the network behavior and performance using two DTN routing protocols, Epidemic and Spray and Wait, with and without CSR mechanisms. The results show that CSR mechanisms improve the performance of VDTN networks significantly.Part of this work has been supported by the Instituto de Telecomunicações, Next Generation Networks and Applications Group (NetGNA), Portugal in the framework of the Project VDTN@Lab, and by the Euro-NF Network of Excellence from the Seventh Framework Programme of EU, in the framework of the Specific Joint Research Project VDTN
Information and Data Distribution System for Rural Areas of Indonesia
Abstract. Internet becomes critical infrastructure in the distribution of information. The information is used for decision making and ensure the success of human activities. However, the distribution of information in rural Indonesia is inconvenient, because the digital communication infrastructure (internet) doesn’t cover all areas in Indonesia. This problem causes the digital divide in Indonesia. This study proposes communications infrastructure and data transfer mechanism or media sharing that can be applied to a variety of rural areas conditions in Indonesia, which has limited communications infrastructure. The approach is to build low power digital carrier devices in the form of minicomputer and utilize Delay or Disruptions Tolerant Network (DTN) architecture. Testing results in the digital carrier node show that the data is successfully delivered.
Keywords: Rural Area, Mini-PC, Delay Tolerant Networ
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GSAF: 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 paper 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. Our extensive evaluation shows that GSAF is efficient, in terms of message delivery ratio and latency as well as network overhead
Experience with Delay-Tolerant Networking from Orbit
We describe the first use from space of the Bundle Protocol for Delay-Tolerant Networking (DTN) and lessons learned from experiments made and experience gained with this protocol. The Disaster Monitoring Constellation (DMC), constructed by Surrey Satellite Technology Ltd (SSTL), is a multiple-satellite Earth-imaging low-Earth-orbit sensor network in which recorded image swaths are stored onboard each satellite and later downloaded from the satellite payloads to a ground station. Store-and-forward of images with capture and later download gives each satellite the characteristics of a node in a disruption-tolerant network. Originally developed for the Interplanetary Internet, DTNs are now under investigation in an Internet Research Task Force (IRTF) DTN research group (RG), which has developed a bundle architecture and protocol. The DMC is technically advanced in its adoption of the Internet Protocol (IP) for its imaging payloads and for satellite command and control, based around reuse of commercial networking and link protocols. These satellites use of IP has enabled earlier experiments with the Cisco router in Low Earth Orbit (CLEO) onboard the constellation s UK-DMC satellite. Earth images are downloaded from the satellites using a custom IP-based high-speed transfer protocol developed by SSTL, Saratoga, which tolerates unusual link environments. Saratoga has been documented in the Internet Engineering Task Force (IETF) for wider adoption. We experiment with the use of DTNRG bundle concepts onboard the UK-DMC satellite, by examining how Saratoga can be used as a DTN convergence layer to carry the DTNRG Bundle Protocol, so that sensor images can be delivered to ground stations and beyond as bundles. Our practical experience with the first successful use of the DTNRG Bundle Protocol in a space environment gives us insights into the design of the Bundle Protocol and enables us to identify issues that must be addressed before wider deployment of the Bundle Protocol. Published in 2010 by John Wiley & Sons, Ltd. KEY WORDS: Internet; UK-DMC; satellite; Delay-Tolerant Networking (DTN); Bundle Protoco
Prioritization of Traffic for Resource Constrained Delay Tolerant Networks
In networks with common shared wireless medium, the available bandwidth is always valuable and often scarce resource. In addition to it, memory available at nodes (eg., sensor nodes) might be limited relative to the amount of information that needs to be stored locally. As Delay Tolerant Networks (DTNs) rely on node mobility for data dissemination, the high node mobility limits the duration of contact. Besides the issue of contact opportunities between nodes, the bandwidth, available storage at peering nodes and contact duration also affect data forwarding. These factors also influence the mechanisms such as buffer replacement and scheduling policies. So there are secondary problems that routing strategies may need to take care of such as to deal with limited resources like buffer, bandwidth and power. Furthermore, despite inherent delay tolerance of most DTN driving applications, there can be situations where some messages may be more important than the others and expected to get delivered earlier. So considering the network limitations and application requirements, the problem of choosing the messages to be transmitted when a contact opportunity arises and the messages to be dropped when buffer full is formulated. A buffer management policy to address these issues is proposed and analysed in this paper. Additionally the buffer utilization of various DTN routing protocols and the impact of buffer size on the performance of DTN are studied
A mobile agent and message ferry mechanism based routing for delay tolerant network
Delay Tolerant Network (DTN) is a class of networks characterized by long delays, frequent disconnections and partitioning of communication paths between network nodes. Due to the frequent disconnection and network partitioning, the overall performance of the network will be deteriorated sharply. The problem is how to make the network fairly connected to optimize data routing and enhance the performance of a network. The aim of this study is to improve the performance of DTN by minimizing end-to-end delivery time and increasing message delivery ratio. Therefore, this research tackles the problem of intermittent connectivity and network partitioning by introducing Agents and Ferry Mechanism based Routing (AFMR). The AFMR comprises of two stages by applying two schemes: mobile agents and ferry mechanism. The agents' scheme is proposed to deal with intermittent connectivity and network partitioning by collecting the basic information about network connection such as signal strength, nodes position in the network and distance to the destination nodes to minimize end-to-end delivery time. The second stage is to increase the message delivery ratio by moving the nodes towards the path with available network connectivity based on agents' feedback. The AFMR is evaluated through simulations and the results are compared with those of Epidemic, PRoPHET and Message Ferry (MF). The findings demonstrate that AFMR is superior to all three, with respect to the average end-to-end delivery time, message delivery ratio, network load and message drop ratio, which are regarded as extremely important metrics for the evaluation of DTN routing protocols. The AFMR achieves improved network performance in terms of end-to-end delivery time (56.3%); enhanced message delivery ratio (60.0%); mitigation of message drop (63.5%) and reduced network load (26.1 %). The contributions of this thesis are to enhance the performance of DTN by significantly overcoming the intermittent connectivity and network partitioning problems in the network
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Efficient geocasting in 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 paper we propose Geocasting Spray And Flood (GSAF), a simple and efficient geocasting protocol for opportunistic networks. GSAF follows an elegant and flexible approach where messages take random walks towards the destination cast. Messages that are routed away from the destination cast are extinct when devices’ buffers get 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. GSAF does that in a privacy-preserving fashion. We also present DA-GSAF, a Direction-Aware extension of GSAF in which messages are forwarded to encountered nodes based on whether a node is moving towards their destination cast. In DA-GSAF only the direction of a mobile node is revealed to other devices. We experimentally evaluate our protocols and compare their performance to prominent geocasting protocols in a very wide set of scenarios, including different maps, mobility models and user populations. Both GSAF and DA-GSAF perform significantly better compared to all other studied protocols, in terms of message delivery ratio, latency and network overhead. DA-GSAF is particularly efficient in sparse scenarios minimising network overhead compared to all other studied protocols. Both GSAF and DA-GSAF perform very well for a wide range of device/user populations indicating that our proposal is viable for crowded and sparse opportunistic networks