Waldir Moreira and Paulo Mendeswaldir.junior@ulusofona.pt

Oct 26th, 2011IEEE Latincom 2011, Belém-PA/Brasil

Opportunistic Networking: Extending Internet Communications Through Spontaneous Networks

2

Agenda

• Introduction

• The case of Delay/Disruption Tolerant Networks

• Use cases

• Routing over Opportunistic Networks

• Future Directions

3

Introduction

4

Picture today

• Users are eager for retrieving/providing information

• Popularization of portable devices

5

Opportunistic Networking

User Willingness

PowerfulDevices

6

Opportunistic Networking

Opportunistic Networking

OppNets 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

Straightforward Definition

• 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

OppNet Elements

• Occasional contacts

• Intermittent connectivity

• Highly mobile and fixed nodes

• Power-constrained devices

• Possible nonexistence of e2e paths

9

General OppNetsCharacteristics

• Disaster and Emergency Networks

• Animal-Tracking Networks

• Sensor Networks

• Inter-Planetary Networks

• Delay/Disruption Tolerant Networks

10

Application Scenarios

11

The case of Delay/Disruption Tolerant

Networks

"to permit interoperation of the Internet resident on Earth with other remotely located internets resident on other planets or spacecraft in transit."

12

Interplanetary Internet

[9] Interplanetary Internet Home

13

Interplanetary Internet

[13] A. McMahon, S. Farrell. Delay- and Disruption-Tolerant Networking, IEEE Internet Computing, 2009

• 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

IPN Characteristics

• 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

History

Occasionally-connected networks where partitions are rather frequent

16

Simple DTN Definition

• New networks do not have what it takes:

- Continuous, bidirectional e2e paths

- Short round-trips

- Symmetric data rates

- Low error rates

17

Regular Assumptions

• DTNs can cope:

- Intermitent connectivity

- Long/Variable delay

- Asymmetric data rates

- High error rates

18

Why the need for DTN?

• 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

DTN Architecture

20

Store-Carry-and-Forward Paradigm

[16] W. Moreira and P. Mendes, “Survey on opportunistic routing for delay tolerant networks,” SITI, University Lusofona, February, 2011

21

Use Cases

• Disruptive environments:

- Sparse scenarios where communication is established through sporadic contacts

• Urban environments

-Dense scenarios with communication suffering different interference levels

22

Different Environments

• 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

Disruptive EnvironmentsDeep Space Communications

24

Disruptive EnvironmentsDeep Space Communications

[19] News on Deep Space Networking[12] Mars Reconnaissance Orbiter

• 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

Disruptive EnvironmentsNoise Monitoring

• 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

Disruptive Environments Networks for Developing World

27

Disruptive Environments Networks for Developing World

[10] S. Jain, K. Fall, R. Patra, Routing in a delay tolerant network, 2004[20] News on Pigeon Carrier

• Purpose: keep track of seismic activity

• Main challenges: very long delays

• Function: activity is relayed through nodes until reaches the sink

28

Disruptive Environments Earthquake Monitoring

29

Disruptive Environments Earthquake Monitoring

[14] Middle America Subduction Experiment (MASE)

• 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

Disruptive Environments Undersea Acoustic Networking

31

Disruptive Environments Undersea Acoustic Networking

[21] Seaweb Network

• 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

Disruptive Environments Zebranet

33

Disruptive Environments Zebranet

• 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

Disruptive EnvironmentsSámi Network Connectivity

• 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

Disruptive Environments Tactical Military Networks

36

Disruptive Environments Tactical Military Networks

[15] MITRE Corporation (C2 On-the-Move Network, Digital Over-the-Horizon Relay)

• 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

Urban Environments Opportunistic Sensing

38

Urban Environments Opportunistic Sensing

[3] CamMobSens - Cambridge University Pollution Monitoring Initiative

39

Routing over Opportunistic Networks

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

What is it about?

41

2000-2010 Analysis

[16] W. Moreira and P. Mendes, “Survey on opportunistic routing for delay tolerant networks,” SITI, University Lusofona, February, 2011

42

Existing Taxonomies

[16]

43

Major Routing Families

[16] W. Moreira and P. Mendes, “Survey on opportunistic routing for delay tolerant networks,” SITI, University Lusofona, February, 2011

• Function: replicate messages at every encounter

• Advantages: optimal delivery probability

• Disadvantages: elevated resource consumption

44

Flooding-basedApproaches

• Epidemic

45

Flooding-basedApproaches

[24] A. Vahdat, D. Becker, Epidemic routing for partially connected ad hoc networks, Tech. Rep. CS-200006, Duke University, 2000.

• Function: only one copy of the message traverses the network

• Advantages: spare resources

• Disadvantages: low delivery rate and high delay

46

Forwarding-basedApproaches

• Direct transmission

- Forwarding only to the destination

• Utility-based routing with 1-hop diffusion

- Function based on encounter timers

47

Forwarding-basedApproaches

[23] T. Spyropoulos, K. Psounis, C. S. Raghavendra, Efficient routing in intermittently connected mobile networks: the single-copy case, 2008

• Function: spread enough copies to quickly reach destination

• Advantages: increase delivery probability while sparing resources

• Disadvantages: metadata overhead

48

Replication-basedApproaches

• Encounter-based

• Resource Usage

• Social Similarity

49

Replication-basedApproaches

• 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)

50

Replication-based ApproachesEncounter-based

[18] S. Nelson, M. Bakht, R. Kravets, Encounter-based routing in DTNs, 2009

• Aging Encounter: time elapsed since last encounter with destination

- FResher Encounter SearcH(FRESH)

* Time elapsed since last encounter

51

Replication-based ApproachesEncounter-based

[7] H. Dubois-Ferriere, M. Grossglauser, M. Vetterli, Age matters: efficient route discovery in mobile ad hoc networks using encounter ages, 2003

• Aging Message: avoid messages to be kept being forwarded

- Spray and Wait

* Spread L number of copies

* Direct transmission

52

Replication-based ApproachesResource Usage

[22] T. Spyropoulos, K. Psounis, C. S. Raghavendra, Spray and wait: an efficient routing scheme for intermittently connected mobile networks, 2005

• 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

53

Replication-based ApproachesResource Usage

[2] A. Balasubramanian, B. Levine, A. Venkataramani, Dtn routing as a resource allocation problem, 2007

• Since 2007

• Have shown great potential

• Use social relationship

• Much wiser decisions

54

Social Aspects: The New Trend

• Community Detection: creation of communities considering people social relationships

- Bubble Rap

* Forwarding based on community and local/ global centrality

55

Replication-based ApproachesSocial Similarity

[11] P. Hui, J. Crowcroft, E. Yoneki, BUBBLE Rap: Social-based Forwarding in Delay Tolerant Networks, 2011

• 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)

56

Replication-based ApproachesSocial Similarity

[5] P. Costa, C. Mascolo, M. Musolesi, G. P. Picco, Socially-aware routing for publish-subscribe in delay-tolerant mobile ad hoc networks, 2008

• 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

57

Replication-based ApproachesSocial Similarity

[17] A. Mtibaa, M. May, M. Ammar, C. Diot, Peoplerank: Combining social and contact information for opportunistic forwarding, 2010

• 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

58

Drawbacks with Detectionof Social Structures

[8] T. Hossmann, T. Spyropoulos, F. Legendre, Know thy neighbor: Towards optimal mapping of contacts to social graphs for dtn routing, 2010

59

Future Directions

• Lots of users

• Different new types of networking

• Many options to perform forwarding

60

Recap

• Based on destination's community

- e.g., Kclique

61

Community-basedForwarding

[11] P. Hui, J. Crowcroft, E. Yoneki, BUBBLE Rap: Social-based Forwarding in Delay Tolerant Networks, 2011

• Data travels based on interest

• Publish-Subscribe paradigm

• Next-hop node is chosen based on its interest in the message's content

62

Interest-basedForwarding

• Focus on the content and its interested parties

• Data is labeled (which is used to retrieve it)

• Users seamlessly exchange data among themselves

63

Information-CentricForwarding

[1] The FP7 4WARD Project

To FCT for financial support via PhD grant

(SFRH/BD/62761/2009)

64

Acknowledgements

What do you envision ??

65

Your view

[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

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

References

Waldir Moreira and Paulo Mendeswaldir.junior@ulusofona.pt

Oct 26th, 2011IEEE Latincom 2011, Belém-PA/Brasil

Opportunistic Networking: Extending Internet Communications Through Spontaneous Networks