10,100 research outputs found

    VECTORS: Video communication through opportunistic relays and scalable video coding

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    Crowd-sourced video distribution is frequently of interest in the local vicinity. In this paper, we propose a novel design to transfer such content over opportunistic networks with adaptive quality encoding to achieve reasonable delay bounds. The video segments are transmitted between source and destination in a delay tolerant manner using the Nearby Connections Android library. This implementation can be applied to multiple domains, including farm monitoring, wildlife, and environmental tracking, disaster response scenarios, etc. In this work, we present the design of an opportunistic contact based system, and we discuss basic results for the trial runs within our institute.Comment: 13 pages, 6 figures, and under 3000 words for submission to the SoftwareX journa

    Opportunistic Key Management in Delay Tolerant Networks

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    Key Management is considered to be a challenging task in Delay Tolerant Networks (DTNs) operating in environments with adverse communication conditions such as space, due to the practical limitations and constraints prohibiting effective closed loop communications. In this paper we propose opportunistic key management as a more suitable solution for key management in networks requiring opportunistic behaviour. We show that opportunistic key management is better exploited and utilized when used in conjunction with routing decisions by security aware DTN nodes

    HRSON: Home-based Routing for Smartphones in Opportunistic Networks

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    Opportunistic networks are delay-tolerant networks which enable network connectivity while there is limited access to network infrastructure, such as natural disaster happenings. Since opportunistic networks use store-carry-forward mechanism to deliver data, routing algorithms have significant impact on successful data delivery. Due to the Operating System restrictions, creating an opportunistic network using ad-hoc model is not feasible on smartphones and to the best of our knowledge, none of common zero-knowledge routing algorithms have been proposed for a non-ad hoc communication model. In this paper, we propose HRSON, a zero-knowledge routing algorithm in a self-organizing approach that an opportunistic infrastructure-based WiFi network is built to use smartphones. We have deployed our approach in simulated scenario of working days of people, whom are using smartphones, on Helsinki map comparing to common zero-knowledge routing algorithms. The results show that our solution increases the average delivery-rate and lowers delay and commutation overhead

    In Vivo Evaluation of the Secure Opportunistic Schemes Middleware using a Delay Tolerant Social Network

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    Over the past decade, online social networks (OSNs) such as Twitter and Facebook have thrived and experienced rapid growth to over 1 billion users. A major evolution would be to leverage the characteristics of OSNs to evaluate the effectiveness of the many routing schemes developed by the research community in real-world scenarios. In this paper, we showcase the Secure Opportunistic Schemes (SOS) middleware which allows different routing schemes to be easily implemented relieving the burden of security and connection establishment. The feasibility of creating a delay tolerant social network is demonstrated by using SOS to power AlleyOop Social, a secure delay tolerant networking research platform that serves as a real-life mobile social networking application for iOS devices. SOS and AlleyOop Social allow users to interact, publish messages, and discover others that share common interests in an intermittent network using Bluetooth, peer-to-peer WiFi, and infrastructure WiFi.Comment: 6 pages, 4 figures, accepted in ICDCS 2017. arXiv admin note: text overlap with arXiv:1702.0565

    Performance modelling of opportunistic forwarding with exact knowledge

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    The Delay Tolerant Networking paradigm aims to enable communications in disconnected environments where traditional protocols would fail. Opportunistic networks are delay tolerant networks whose nodes are typically the users\u27 personal mobile devices. Communications in an opportunistic network rely on the mobility of users: each message is forwarded from node to node, according to a hop-by-hop decision process that selects the node that is better suited for bringing the message closer to its destination. Despite the variety of forwarding protocols that have been proposed in the recent years, there is no reference framework for the performance modelling of opportunistic forwarding. In this paper we start to fill this gap by proposing an analytical model for the expected delay and the expected number of hops experienced by messages when delivered in an opportunistic fashion. This model seamlessly integrates both social-aware and social-oblivious single-copy forwarding protocols, as well as different hypotheses for user contact dynamics. The proposed framework is used to derive bounds on the expected delay under homogeneous and heterogeneous contact patterns. We found that, in heterogeneous settings, finite expected delay can be guaranteed not only when nodes\u27 inter-meeting times follow an exponential or power law with exponential cut-off distribution, but also when they are power law distributed, as long as weaker conditions than those derived by Chaintreau et al. [1] for the homogeneous scenario are satisfied

    Congestion aware forwarding in delay tolerant and social opportunistic networks

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    We propose an approach for opportunistic forwarding that supports optimization of multipoint high volume data flow transfer while maintaining high buffer availability and low delays. This paper explores a number of social, buffer and delay heuristics to offload the traffic from congested parts of the network and spread it over less congested parts of the network in order to keep low delays, high success ratios and high availability of nodes. We conduct an extensive set of experiments for assessing the performance of four newly proposed heuristics and compare them with Epidemic, Prophet, Spay and Wait and Spay and Focus protocols over real connectivity driven traces (RollerNet) and with a realistic publish subscribe filecasting application. We look into success ratio of answered queries, download times (delays) and availability of buffer across eight protocols for varying congestion levels in the face of increasing number of publishers and topic popularity. We show that all of our combined metrics perform better than Epidemic protocol, Prophet, Spray and Wait, Spray and Focus and our previous prototype across all the assessed criteria

    The Quest for a Killer App for Opportunistic and Delay Tolerant Networks (Invited Paper)

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    Delay Tolerant Networking (DTN) has attracted a lot of attention from the research community in recent years. Much work have been done regarding network architectures and algorithms for routing and forwarding in such networks. At the same time as many show enthusiasm for this exciting new research area there are also many sceptics, who question the usefulness of research in this area. In the past, we have seen other research areas become over-hyped and later die out as there was no killer app for them that made them useful in real scenarios. Real deployments of DTN systems have so far mostly been limited to a few niche scenarios, where they have been done as proof-of-concept field tests in research projects. In this paper, we embark upon a quest to find out what characterizes a potential killer applications for DTNs. Are there applications and situations where DTNs provide services that could not be achieved otherwise, or have potential to do it in a better way than other techniques? Further, we highlight some of the main challenges that needs to be solved to realize these applications and make DTNs a part of the mainstream network landscape

    Store, carry and forward for energy efficiency in multi-hop cellular networks with mobile relays

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    Abstract The wide scale adoption of smartphones is boosting cellular data traffic with the consequent capacity constraints of cellular systems and increase in energy consumption. A significant portion of cellular data traffic can be deemed as delay tolerant. Such tolerance offers possibilities for designing novel communications and networking solutions that can accommodate the delay tolerant cellular data traffic while reducing their impact on the overall cellular capacity and energy consumption. In this context, this work studies the use of opportunistic store, carry and forward techniques in Multi-Hop Cellular Networks (MCN) to reduce energy consumption for delay tolerant traffic. The study focuses on two-hop MCN networks using mobile relays (MCN-MR), and identifies the optimum mobile relay location and the location from which the relay should start forwarding the information to the cellular base station in order to minimize the overall energy consumption. The study shows that the use of opportunistic store, carry and forward techniques in MCN-MR can significantly reduce energy consumption compared to other solutions, including traditional single-hop cellular systems or direct contact store, carry and forward solutions.This work is supported in part by the Spanish Ministry of Economy and Competitiveness and FEDER funds (TEC2011–26109)and the Local Government of Valencia with reference ACIF/2010/161 and BEFPI/2012/06

    Opportunistic Networking for Improving the Energy Efficiency of Multi-Hop Cellular Networks

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    Relaying technologies can help address the capacity and energy-efficiency challenges faced by cellular networks as a result of the rapid increase in mobile data consumption. A nonnegligible portion of such consumption corresponds to delay tolerant services. This delay tolerance offers the possibility for opportunistic networking to exploit contact opportunities between mobile devices in order to reduce the impact of data traffic on the cellular capacity and energy-efficiency without sacrificing the end-user quality of service. In this context, this paper investigates the use of opportunistic forwarding in MCNMR (Multi-hop Cellular Networks with Mobile Relays) to reduce energy consumption in the case of delay tolerant services. The study proposes to exploit context information provided at a low cost by the cellular infrastructure to efficiently select the forwarding node in a two-hop MCN-MR scenario. The proposed solution results in significant energy savings compared to traditional single-hop cellular communications and other forwarding solutions reported in the literatureThis work is supported in part by the Spanish Ministry of Economy and Competitiveness and FEDER funds (TEC201126109),and the Local Government of Valencia with reference ACIF/2010/161 and BEFPI/2012/06
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