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Opportunistic Networking: Congestion, Transfer Ordering and Resilience
Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Division of Computer Systems. Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computer Systems. (Communication Research)
2014 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Opportunistic networks are constructed by devices carried by people and vehicles. The devices use short range radio to communicate. Since the network is mobile and often sparse in terms of node contacts, nodes store messages in their buffers, carrying them, and forwarding them upon node encounters. This form of communication leads to a set of challenging issues that we investigate: congestion, transfer ordering, and resilience.

Congestion occurs in opportunistic networks when a node's buffers becomes full. To be able to receive new messages, old messages have to be evicted. We show that buffer eviction strategies based on replication statistics perform better than strategies that evict messages based on the content of the message.

We show that transfer ordering has a significant impact on the dissemination of messages during time limited contacts. We find that transfer strategies satisfying global requests yield a higher delivery ratio but a longer delay for the most requested data compared to satisfying the neighboring node's requests.

Finally, we assess the resilience of opportunistic networks by simulating different types of attacks. Instead of enumerating all possible attack combinations, which would lead to exhaustive evaluations, we introduce a method that use heuristics to approximate the extreme outcomes an attack can have. The method yields a lower and upper bound for the evaluated metric over the different realizations of the attack. We show that some types of attacks are harder to predict the outcome of and other attacks may vary in the impact of the attack due to the properties of the attack, the forwarding protocol, and the mobility pattern.

Place, publisher, year, edition, pages
Uppsala: Acta Universitatis Upsaliensis, 2014. , 45 p.
Series
Digital Comprehensive Summaries of Uppsala Dissertations from the Faculty of Science and Technology, ISSN 1651-6214 ; 1148
Keyword [en]
Opportunistic Networking, Congestion, Transfer Ordering, Resilience, Testbed, WISENET
National Category
Computer Science Communication Systems
Research subject
Computer Science with specialization in Computer Communication
Identifiers
URN: urn:nbn:se:uu:diva-223492ISBN: 978-91-554-8953-3 (print)OAI: oai:DiVA.org:uu-223492DiVA: diva2:713179
Public defence
2014-06-09, Room 2446, Polacksbacken, Lägerhyddsvägen 2, Uppsala, 13:15 (English)
Opponent
Supervisors
Projects
WISENET
Available from: 2014-05-15 Created: 2014-04-22 Last updated: 2014-07-21Bibliographically approved
List of papers
1. Haggle Testbed: a Testbed for Opportunistic Networks
Open this publication in new window or tab >>Haggle Testbed: a Testbed for Opportunistic Networks
2011 (English)In: In Proceedings of the 7th Swedish National Computer Networking Workshop, 2011Conference paper, Published paper (Refereed)
Identifiers
urn:nbn:se:uu:diva-155530 (URN)
Projects
Haggle
Available from: 2011-06-23 Created: 2011-06-23 Last updated: 2014-06-30
2. Congestion Avoidance in a Data-Centric Opportunistic Network
Open this publication in new window or tab >>Congestion Avoidance in a Data-Centric Opportunistic Network
2011 (English)In: Proceedings of the 2011 ACM SIGCOMM Workshop on Information-Centric Networking (ICN-2011), 2011Conference paper, Published paper (Refereed)
Identifiers
urn:nbn:se:uu:diva-155528 (URN)
Projects
ResumeNet
Available from: 2011-06-23 Created: 2011-06-23 Last updated: 2014-06-30
3. Making the Most of Your Contacts: Transfer Ordering in Data-Centric Opportunistic Networks
Open this publication in new window or tab >>Making the Most of Your Contacts: Transfer Ordering in Data-Centric Opportunistic Networks
Show others...
2012 (English)In: Proceedings of the 2012 ACM MobiOpp Workshop on Mobile Opportunistic Networks, Zürich: ACM Press, 2012Conference paper, Published paper (Refereed)
Abstract [en]

Opportunistic networks use unpredictable and time-limited con- tacts to disseminate data. Therefore, it is important that protocols transfer useful data when contacts do occur. Specifically, in a data- centric network, nodes benefit from receiving data relevant to their interests. To this end, we study five strategies to select and order the data to be exchanged during a limited contact, and measure their ability to promptly and efficiently deliver highly relevant data.

Our trace-driven experiments on an emulation testbed suggest that nodes benefit in the short-term from ordering data transfers to satisfy local interests. However, this can lead to suboptimal longterm system performance. Restricting sharing based on matching nodes’ interests can lead to segregation of the network, and limit useful dissemination of data. A non-local understanding of other nodes’ interests is necessary to effectively move data across the network. If ordering of transfers for data relevance is not explicitly considered performance is comparable to random, which limits the delivery of individually relevant data. 

Place, publisher, year, edition, pages
Zürich: ACM Press, 2012
National Category
Communication Systems
Identifiers
urn:nbn:se:uu:diva-171587 (URN)
Conference
ACM MobiOpp
Projects
ResumeNet
Available from: 2012-03-22 Created: 2012-03-22 Last updated: 2014-06-30
4. Resilience and Opportunistic Forwarding: Beyond Average Value Analysis
Open this publication in new window or tab >>Resilience and Opportunistic Forwarding: Beyond Average Value Analysis
Show others...
2014 (English)In: Computer Communications, ISSN 0140-3664, E-ISSN 1873-703X, Vol. 48, no SI, 111-120 p.Article in journal (Refereed) Published
Abstract [en]

Opportunistic networks are systems with highly distributed operation, relying on the altruistic cooperation of highly heterogeneous, and not always software and hardware-compatible, user nodes. Moreover, the absence of central coordination and control makes them vulnerable to malicious attacks. In this paper, we study the resilience of popular forwarding protocols to a representative set of challenges to their normal operation. These include jamming locally disturbing message transfer between nodes, hardware/software failures and incompatibility among nodes rendering contact opportunities useless, and free-riding phenomena. We first formulate and promote the metric envelope concept as a tool for assessing the resilience of opportunistic forwarding schemes. Metric envelopes depart from the standard practice of average value analysis and explicitly account for the differentiated challenge impact due to node heterogeneity (device capabilities, mobility) and attackers’ intelligence. We then propose heuristics to generate worst- and best-case challenge realization scenarios and approximate the lower and upper bounds of the metric envelopes. Finally, we demonstrate the methodology in assessing the resilience of three popular forwarding protocols in the presence of the three challenges, and under a comprehensive range of mobility patterns. The metric envelope approach provides better insights into the level of protection path diversity and message replication provide against different challenges, and enables more informed choices in opportunistic forwarding when network resilience becomes important.

National Category
Communication Systems
Identifiers
urn:nbn:se:uu:diva-222822 (URN)10.1016/j.comcom.2014.04.004 (DOI)000337883200010 ()
Projects
ResumeNet, WISENET
Funder
EU, FP7, Seventh Framework Programme, FP7-224619
Note

Special Issue

Available from: 2014-04-17 Created: 2014-04-14 Last updated: 2014-07-25Bibliographically approved

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