Date post: | 26-Dec-2015 |
Category: |
Documents |
Upload: | bethany-gibbs |
View: | 217 times |
Download: | 0 times |
Introduction to Delay Tolerant Networks
Tzu-Chieh TsaiDepartment of Computer Science, National Cheng Chi University
Outline Introduction
How does it works? Key Properties of DTNs
Potential Applications Summary
Future Wireless Internet
Slide from “DTNs and Sensor Networks”, Myung-Ki Shin at Future Internet Camp, August 2007.
Introduction Core function of communication network
Routing Find a path from a source to some destinations
Traditional routing solutions Assume that there exists an end-to-end path
between communicating nodes Delay/disruption tolerant networks
Communication is possible even if end-to-end connectivity is never achievable
Exploiting node’s mobility Using store-carry-forward fashion
D
SData
Traditional Routing
Traditional Routing
How does it work?
D
S
R
Store Carry Forward
Store Carry Forward
StoreStore
ForwardForward
Data
How does it work?
CarryCarry
Bagel = Source
Bagel = Source
Ants = Relay
Ants = Relay
Fact 1: Wireless is everywhere !
Fact 1: Wireless is everywhere ! Fact 2: We need mobility!
Fact 1: Wireless is everywhere ! Fact 2: We need mobility! Fact 3: Storage is cheap and vast!
Opportunistic NetworksOpportunistic Networks
Opportunistic Networks vs Internet
Key Properties of DTNs High Latency
Any two nodes may never meet each other. Low Data Rate
Due to the long latency of data delivery. Disconnection
It is hard to find an end-to-end path. Long Queuing Delay
Because of the disconnection. Short Range Contact
Only one-hop communication is guaranteed. Dynamic Network Topology
Different types of user behavior will result in dramatically different network conditions.
Outline Introduction
How does it works? Key Properties of DTNs
Potential Applications Summary
Potential Applications Telemedicine for Developing Regions DTN-based Social Network Service Communication in the Presence of Oppressive
Governments File Sharing and Bulk Data Transfer Share Air Minutes
Telemedicine for Developing Regions Store-Carry-forward Voice-over-IP
telemedicine system Improve the possibility for doctors to give
correct diagnose and prescribe treatment from remote location
Benefit Can be used by those who lack computer skills. Open source software is relatively cheap. Can be deployed without fixed infrastructure
Challenge Long delay would causes some disruption in voice
quality.M. Chetty, W. Tucker, and E. Blake. Developing locally relevant applications for rural areas: A south african example. In SAICSIT, 2004.
DTN-based Social Network Service DTN-based Short Message Service Example: A farmer can send a advertisement
message to his friends, and the friends can help to propagate the message through the social network.
Benefit A more convenient way to find and exchange
information than traditional face-to-face communication
Challenge Need to find incentive mechanisms to convince
end user to use the system
B. E. Kolko, E. J. Rose, and E. J. Johnson.Communication as information-seeking: the case for mobile social software for developing regions. In Proc. of WWW ’07, 2007.
Communication in the Presence of Oppressive Governments Anonymous Delay Tolerant Networks Opportunistic forwarding message between
people Much more difficult for government agencies
to track the communication. Benefit
Using mobility and delay of transmission to increase anonymity.
Challenge How to avoid rogue agents injecting fake
acknowledgements to purge messages from the network?
R. Dingledine, N. Mathewson, and P. Syverson. Tor:The second-generation onion router. In Proceedings of the 13th USENIX Security Symposium, August 2004.
File Sharing and Bulk Data Transfer Use the cellular network to transmit the request
for some content, and then use delay tolerant techniques to deliver the data to the mobile device.
It’s more beneficial if the data access patterns are somehow localized such that users in a certain area are more likely to request a certain data item.
Benefit File data would rapidly be shared between a large part
of population with less resource usage. Challenge
Copyright and DRM issuesN. Laoutaris, G. Smaragdakis, R. Sundaram, and P. Rodriguez. Delay-Tolerant Bulk Data Transfer on the Internet. In Proceedings of ACM SIGMETRICS 2009, Seattle, WA, June 2009.
Share Air Minutes Allowing the contract users to share their
excess air minutes to the prepaid card users. The shared phone acting as the server then
diverts the voice traffic to the cellular network via the phone’s cellular link.
Benefit Contract users sell their unused minutes Pre-pay users could still use the calling service Operators can gain the value of the resold
minutes. Challenge
How to deal with the micro-payments?P. Hui, R. Mortier, K. Xu, J. Crowcroft, and V. O. Li.Sharing airtime with shair avoids wasting time and money. In Proc. of HotMobile 2009, February 2009.
Outline Introduction
How does it works? Key Properties of DTNs
Research Issues Mobility Pattern Analysis Routing Protocol Design
Potential Applications Summary
Summary Characteristics of DTN
No end-to-end path Intermittent connectivity Dynamic topology Long delay
DTN routing Flooding-based: redundancy Forwarding-based: require topology information
Potential Application Urban area: DTN-based Social Network Service Developing region: Low cost communication
solutions