Opportunistic Networking: Extending Internet Communications Through Spontaneous Networks

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The increasing number of personal devices with wireless communication capabilities makes it possible the creation of spontaneous networks in which devices communicate occasionally depending on contact opportunities. This intermittent communication may be due to mobility and power-limitations of devices, physical obstacles and distance, resulting in the possible nonexistence of end-to-end paths toward a destination. In summary, spontaneous networks are characterized by being highly dynamic, composed of mobile and static nodes that are able to take advantage of opportunistic time-varying contacts.

This tutorial aims to give an introduction to the challenges and research issues behind the development of
opportunistic networking solutions able to boost the deployment of spontaneous networks. Special attention will be
given to the fundamental building block: routing over opportunistic networks. Since the effciency of spontaneous
networks depends upon the way contacts occur between carriers of communication devices, special attention will
also be given to the analysis of method to detect social structures based on opportunistic contacts. To emphasize
the impact that opportunistic networking technology may have, this tutorial ends up with the description of major
aspects of future forwarding schemes: interest-based and information-centric forwardings.

This presentation was given as a tutorial in the IEEE 3rd Latin-American Conference on Communications (LATINCOM), on Oct 26th, 2011, in Belém/PA, Brazil.
http://www.ieee-latincom.ufpa.br/

Published in: Technology

Opportunistic Networking: Extending Internet Communications Through Spontaneous Networks

  1. 1. Opportunistic Networking: Extending InternetCommunications Through Spontaneous Networks Waldir Moreira and Paulo Mendes waldir.junior@ulusofona.pt Oct 26th, 2011 IEEE Latincom 2011, Belém-PA/Brasil
  2. 2. Agenda• Introduction• The case of Delay/Disruption Tolerant Networks• Use cases• Routing over Opportunistic Networks• Future Directions 2
  3. 3. Introduction 3
  4. 4. Picture today• Users are eager for retrieving/providing information• Popularization of portable devices 4
  5. 5. Opportunistic Networking User Willingness Powerful Devices 5
  6. 6. Opportunistic Networking Opportunistic Networking 6
  7. 7. Straightforward DefinitionOppNets are highly dynamic, composed of mobile and static nodes (i.e., devices) and take advantages of opportunistic time- varying contacts among users carrying them to exchange information 7
  8. 8. OppNet Elements• Nodes- PDAs, cell phones, anything with networking capabilities• Contacts- Scheduled (i.e., mules, buses, LEO satellites)- Opportunistic (i.e., random contact with a strange)• Information- Anything that can deal with the high queueing delays 8
  9. 9. General OppNetsCharacteristics• Occasional contacts• Intermittent connectivity• Highly mobile and fixed nodes• Power-constrained devices• Possible nonexistence of e2e paths 9
  10. 10. Application Scenarios• Disaster and Emergency Networks• Animal-Tracking Networks• Sensor Networks• Inter-Planetary Networks• Delay/Disruption Tolerant Networks 10
  11. 11. The case of Delay/Disruption Tolerant Networks 11
  12. 12. Interplanetary Internet"to permit interoperation of the Internet resident on Earth with other remotely located internets resident on other planets or spacecraft in transit."[9] Interplanetary Internet Home 12
  13. 13. Interplanetary Internet[13] A. McMahon, S. Farrell. Delay- and Disruption-Tolerant Networking,IEEE Internet Computing, 2009 13
  14. 14. IPN Characteristics• Significant propagation delays- 4 minutes one-way light-trip time between Earth and Mars• Intermittent connectivity- Planetary movement• Low and highly asymmetric bandwidth• Relatively high bit-error rate 14
  15. 15. History• Interplanetary Internet envisioned by Vint Cerf (1997)• Collaboration between Cerf and NASA’s Jet Propulsion Laboratory (1998)• Interplanetary Internet Research Group (IPNRG)• Interplanetary Internet (IPN): Architectural Definition (2001)• Delay-Tolerant Network Architecture: The Evolving Interplanetary Internet (2002)• IPNRG -> DTNRG• Delay-Tolerant Networking Architecture (2007) 15
  16. 16. Simple DTN DefinitionOccasionally-connected networks where partitions are rather frequent 16
  17. 17. Regular Assumptions• New networks do not have what it takes:- Continuous, bidirectional e2e paths- Short round-trips- Symmetric data rates- Low error rates 17
  18. 18. Why the need for DTN?• DTNs can cope:- Intermitent connectivity- Long/Variable delay- Asymmetric data rates- High error rates 18
  19. 19. DTN Architecture• Bundle layer- e2e message-oriented overlay based on hop-by-hop transfer with persistent storage to overcome network interruption- Focus on reliable transport structure than in routing itself 19
  20. 20. Store-Carry-and-ForwardParadigm[16] W. Moreira and P. Mendes, “Survey on opportunistic routing for delaytolerant networks,” SITI, University Lusofona, February, 2011 20
  21. 21. Use Cases 21
  22. 22. Different Environments• Disruptive environments:- Sparse scenarios where communication is established through sporadic contacts• Urban environments-Dense scenarios with communication suffering different interference levels 22
  23. 23. Disruptive EnvironmentsDeep Space Communications• Purpose: provide communication means for manned/robotic exploration• Main challenges: very long delays, sparseness, shadow areas and spacecraft lifetime• Function: Information and commands are exchanged between landers/rovers and earth station through orbiters 23
  24. 24. Disruptive EnvironmentsDeep Space Communications[19] News on Deep Space Networking[12] Mars Reconnaissance Orbiter 24
  25. 25. Disruptive EnvironmentsNoise Monitoring• Purpose: keep track of noise to ensure acceptable levels• Main challenges: high cost of equipments and communication medium• Function: buses (i.e., data mules) collect data from monitoring stations 25
  26. 26. Disruptive EnvironmentsNetworks for Developing World• Purpose: provide asynchronous Internet access despite the scarce/expensive infrastructure• Main challenges: long delays and scarce/expensive infrastructure• Function: data is sent/retrieved either through USB stick carried by a motorbiker or via dial-up connection 26
  27. 27. Disruptive EnvironmentsNetworks for Developing World[10] S. Jain, K. Fall, R. Patra, Routing in a delay tolerant network, 2004[20] News on Pigeon Carrier 27
  28. 28. Disruptive EnvironmentsEarthquake Monitoring• Purpose: keep track of seismic activity• Main challenges: very long delays• Function: activity is relayed through nodes until reaches the sink 28
  29. 29. Disruptive EnvironmentsEarthquake Monitoring[14] Middle America Subduction Experiment (MASE) 29
  30. 30. Disruptive EnvironmentsUndersea Acoustic Networking• Purpose: provide connectivity to autonomous underwater vehicles• Main challenges: delay, and challenging medium• Function: information exchanged between AUV/subs and command center through repeaters, buoys, and sattelite links 30
  31. 31. Disruptive EnvironmentsUndersea Acoustic Networking[21] Seaweb Network 31
  32. 32. Disruptive EnvironmentsZebranet• Purpose: Study zebra movements through collars carried by them• Main challenges: energy constraints• Function: collars opportunistically exchange GPS location later then obtained by scientists 32
  33. 33. Disruptive EnvironmentsZebranet 33
  34. 34. Disruptive EnvironmentsSámi Network Connectivity• Purpose: provide location information on reindeer herds• Main challenges: very little infrastructure and sparseness• Function: herds locations is carried on snowmobiles back to villages 34
  35. 35. Disruptive EnvironmentsTactical Military Networks• Purpose: establish quick communication means among military soldiers, vehicles, and aircrafts• Main challenges: high disruption and partition• Function: information is relayed among military units 35
  36. 36. Disruptive EnvironmentsTactical Military Networks[15] MITRE Corporation (C2 On-the-Move Network, Digital Over-the-Horizon Relay) 36
  37. 37. Urban EnvironmentsOpportunistic Sensing• Purpose: gather information from sensing systems• Main challenges: short contact times• Function: sensor present in different devices gather information which is then collected mobile devices (i.e., custodian) to be transfered to the sensing system central 37
  38. 38. Urban EnvironmentsOpportunistic Sensing[3] CamMobSens - Cambridge University Pollution Monitoring Initiative 38
  39. 39. Routing overOpportunistic Networks 39
  40. 40. What is it about?Considers any contact among nodes and forwarding decisions are made using locally collected knowledge about node behavior to predict which nodes are likely to deliver a content or bring it closer to the destination 40
  41. 41. 2000-2010 Analysis[16] W. Moreira and P. Mendes, “Survey on opportunistic routing for delaytolerant networks,” SITI, University Lusofona, February, 2011 41
  42. 42. Existing Taxonomies[16] 42
  43. 43. Major Routing Families[16] W. Moreira and P. Mendes, “Survey on opportunistic routing for delaytolerant networks,” SITI, University Lusofona, February, 2011 43
  44. 44. Flooding-basedApproaches• Function: replicate messages at every encounter• Advantages: optimal delivery probability• Disadvantages: elevated resource consumption 44
  45. 45. Flooding-basedApproaches• Epidemic[24] A. Vahdat, D. Becker, Epidemic routing for partially connected ad hocnetworks, Tech. Rep. CS-200006, Duke University, 2000. 45
  46. 46. Forwarding-basedApproaches• Function: only one copy of the message traverses the network• Advantages: spare resources• Disadvantages: low delivery rate and high delay 46
  47. 47. Forwarding-basedApproaches• Direct transmission - Forwarding only to the destination• Utility-based routing with 1-hop diffusion - Function based on encounter timers[23] T. Spyropoulos, K. Psounis, C. S. Raghavendra, Efficient routing inintermittently connected mobile networks: the single-copy case, 2008 47
  48. 48. Replication-basedApproaches• Function: spread enough copies to quickly reach destination• Advantages: increase delivery probability while sparing resources• Disadvantages: metadata overhead 48
  49. 49. Replication-basedApproaches• Encounter-based• Resource Usage• Social Similarity 49
  50. 50. Replication-based ApproachesEncounter-based• Frequency Encounter: history of encounters with a specific destination- Encounter-Based Routing (EBR) * Counts the number of contacts (Current Window Counter) * Determines node’s past rate of encounters (Encounter Value)[18] S. Nelson, M. Bakht, R. Kravets, Encounter-based routing in DTNs,2009 50
  51. 51. Replication-based ApproachesEncounter-based• Aging Encounter: time elapsed since last encounter with destination - FResher Encounter SearcH (FRESH) * Time elapsed since last encounter[7] H. Dubois-Ferriere, M. Grossglauser, M. Vetterli, Age matters: efficientroute discovery in mobile ad hoc networks using encounter ages, 2003 51
  52. 52. Replication-based ApproachesResource Usage• Aging Message: avoid messages to be kept being forwarded - Spray and Wait * Spread L number of copies * Direct transmission[22] T. Spyropoulos, K. Psounis, C. S. Raghavendra, Spray and wait: anefficient routing scheme for intermittently connected mobile networks,2005 52
  53. 53. Replication-based ApproachesResource Usage• Resource Allocation: forwarding decisions that wisely use available resources - RAPID * Replication occurs based on the effect that it may have on a predefined performance metric[2] A. Balasubramanian, B. Levine, A. Venkataramani, Dtn routing as aresource allocation problem, 2007 53
  54. 54. Social Aspects:The New Trend• Since 2007• Have shown great potential• Use social relationship• Much wiser decisions 54
  55. 55. Replication-based ApproachesSocial Similarity• Community Detection: creation of communities considering people social relationships- Bubble Rap * Forwarding based on community and local/ global centrality[11] P. Hui, J. Crowcroft, E. Yoneki, BUBBLE Rap: Social-based Forwarding inDelay Tolerant Networks, 2011 55
  56. 56. Replication-based ApproachesSocial Similarity• Shared Interests: nodes with the same interest as destination are good forwarders- SocialCast * predicted node’s co-location (probability of nodes being co-located with others) * change in degree of connectivity (mobility and changes in neighbor sets)[5] P. Costa, C. Mascolo, M. Musolesi, G. P. Picco, Socially-aware routing forpublish-subscribe in delay-tolerant mobile ad hoc networks, 2008 56
  57. 57. Replication-based ApproachesSocial Similarity• Node Popularity: use of social information to generate ranks to nodes based on their position on a social graph - PeopleRank * Forwarding based on social ranking of nodes[17] A. Mtibaa, M. May, M. Ammar, C. Diot, Peoplerank: Combining socialand contact information for opportunistic forwarding, 2010 57
  58. 58. Drawbacks with Detectionof Social Structures• Community detection, shared interests, node popularity• Communities are statically defined• Do not consider the age of contacts when computing the centrality• Strong assumptions• Full knowledge on social information is not enough• Some social metrics (e.g., betweenness centrality) can lead to node homogeneity[8] T. Hossmann, T. Spyropoulos, F. Legendre, Know thy neighbor: Towardsoptimal mapping of contacts to social graphs for dtn routing, 2010 58
  59. 59. Future Directions 59
  60. 60. Recap• Lots of users• Different new types of networking• Many options to perform forwarding 60
  61. 61. Community-basedForwarding• Based on destinations community- e.g., Kclique[11] P. Hui, J. Crowcroft, E. Yoneki, BUBBLE Rap: Social-based Forwarding inDelay Tolerant Networks, 2011 61
  62. 62. Interest-basedForwarding• Data travels based on interest• Publish-Subscribe paradigm• Next-hop node is chosen based on its interest in the messages content 62
  63. 63. Information-CentricForwarding• Focus on the content and its interested parties• Data is labeled (which is used to retrieve it)• Users seamlessly exchange data among themselves[1] The FP7 4WARD Project 63
  64. 64. AcknowledgementsTo FCT for financial support via PhD grant(SFRH/BD/62761/2009) 64
  65. 65. Your viewWhat do you envision ?? 65
  66. 66. References[1] 4WARD Project, The FP7 - http://www.4ward-project.eu/index.php?id=29[2] A. Balasubramanian, B. Levine, A. Venkataramani, Dtn routing as a resource allocation problem, in: Proceedings of ACM SIGCOMM, Kyoto, Japan, August, 2007.[3] CamMobSens - Cambridge University Pollution Monitoring Initiative - http://www.escience.cam.ac.uk/mobiledata/[4] V. Cerf, S. Burleigh, A. Hooke, L. Torgerson, R. Durst, K. Scott, K. Fall, H. Weiss, Delay tolerant network architecture, IETF Network Working Group. RFC 4838, 2007.[5] P. Costa, C. Mascolo, M. Musolesi, G. P. Picco, Socially-aware routing for publish-subscribe in delay-tolerant mobile ad hoc networks, Selected Areas in Communications, IEEE Journal on 26 (5) (2008) 748–760.[6] Delay-Tolerant Networks Home - http://www.dtnrg.org/[7] H. Dubois-Ferriere, M. Grossglauser, M. Vetterli, Age matters: efficient route discovery in mobile ad hoc networks using encounter ages, in: Proceedings of ACM MobiHoc, Annapolis, USA, June, 2003.[8] T. Hossmann, T. Spyropoulos, F. Legendre, Know thy neighbor: Towards optimal mapping of contacts to social graphs for dtn routing, in: Proceedings of IEEE INFOCOM, San Diego, USA, March, 2010.[9] Interplanetary Internet Home - http://www.ipnsig.org/[10] S. Jain, K. Fall, R. Patra, Routing in a delay tolerant network, in: Proceedings of the ACM SIGCOMM, Portland, USA, August,2004.[11] P. Hui, J. Crowcroft, E. Yoneki, BUBBLE Rap: Social-based Forwarding in Delay Tolerant Networks, To appear in: Mobile Computing, IEEE Transactions on, 2011.[12] Mars Reconnaissance Orbiter - http://www.nasa.gov/mission_pages/MRO/news/mro-20060912.html[13] A. McMahon, S. Farrell. Delay- and Disruption-Tolerant Networking. IEEE Internet Computing, 2009. 66
  67. 67. References[14] Middle America Subduction Experiment (MASE) - http://www.gps.caltech.edu/~clay/MASEdir/MASEprogress_report.html#Figure1[15] MITRE Corporation (US Marine Corps) (Presentation on C2 On-the-Move Network, Digital Over-the-Horizon Relay) - http://www.ietf.org/proceedings/65/slides/DTNRG-2.pdf[16] W. Moreira and P. Mendes, “Survey on opportunistic routing for delay tolerant networks,” Tech. Rep. SITI-TR-11-02, Research Unit in Informatics Systems and Technologies (SITI), University Lusofona, February, 2011.[17] A. Mtibaa, M. May, M. Ammar, C. Diot, Peoplerank: Combining social and contact information for opportunistic forwarding, in: Proceedings of INFOCOM, San Diego, USA, March, 2010.[18] S. Nelson, M. Bakht, R. Kravets, Encounter-based routing in DTNs, in: Proceedings of INFOCOM, Rio de Janeiro, Brazil, April, 2009.[19] News on Deep Space Networking - http://www.engadget.com/2008/11/19/nasas-interplanetary-internet-tests-a- success-vint-cerf-triump/[20] News on Pigeon Carrier - http://www.dailymail.co.uk/news/article-1212333/Pigeon-post-faster-South-Africas- Telkom.html[21] Seaweb Network (Presentation)- http://www.ietf.org/proceedings/65/slides/DTNRG-14.pdf[22] T. Spyropoulos, K. Psounis, C. S. Raghavendra, Spray and wait: an efficient routing scheme for intermittently connected mobile networks, in: Proceedings of ACM SIGCOMM WDTN, Philadelphia, USA, August, 2005.[23] T. Spyropoulos, K. Psounis, C. S. Raghavendra, Efficient routing in intermittently connected mobile networks: the single-copy case, IEEE/ACM Trans. Netw. 16 (1) (2008) 63–76.[24] A. Vahdat, D. Becker, Epidemic routing for partially connected ad hoc networks, Tech. Rep. CS-200006, Duke University, 2000.[25] F. Warthman, Delay-tolerant networks (dtns): A tutorial, Warthman Associates. Version 1.1, May, 2003. 67
  68. 68. Opportunistic Networking: Extending InternetCommunications Through Spontaneous Networks Waldir Moreira and Paulo Mendes waldir.junior@ulusofona.pt Oct 26th, 2011 IEEE Latincom 2011, Belém-PA/Brasil

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