Trends and Challenges in Delay Tolerant Network (DTN) or Mobile Opportunis<c Network (OppNet)
Special Talk on: Dr. Mazlan Abbas, UTHM 2 April 2014
A little bit about the Speaker
Outline
• Motivation • History of DTN • Trends and Challenges in DTN • Routing in DTN • Performance of DTN in Emergency Scenario • DTN Applications • Future Work
Issues of Communications During Disasters and Emergency
Terrorist Attack Hurricane
Tsunami Earthquake
Lack of adequate communications
Opportunistic Networks (OppNets)
To enable communication between source and destination without the support of a fixed network infrastructure
6
3G
3G
3G 3G Base station
Normal
7
3G
3G
3G 3G Base station
During Disaster
X X
X X
History of the DTN Motivation
Imagine This… If I say a “Hello” to you and you hear it
after … 9 hours!!!
Some Fast facts
Time taken by light – Earth – Jupiter : 32.7 min – Earth – Saturn : 76.7 min – Earth – Pluto : 5.5 hours – Earth – Voyager1 : 13 hours – Earth – Voyager2 : 10.4 hours.
[Source: TERENA Networking Conference 2000, 24 May 2000, Scott Burleigh, Vint Cerf, Bob Durst, Adrian Hooke, Keith Scott, Eric Travis, Howard Weiss
History of Delay Tolerant Network
• Interplanetary Internet (IPN) is a NASA research project led by Vint Cerf in 1998.
• The basic idea is to try to make data communications in space/ between planets.
• IPN became the most fundamental basis for DTN architecture and protocol suite.
• The Interplanetary Internet is a disconnected, store-and forward ‘network of Internets’ based on a wireless backbone with huge delays (The delay in sending or receiving data from Mars takes between 3.5 to 20 minutes at the speed of light) and error prone links
• Failing of IP/TCP in space missions – End-to-end path exist – Small delays
Delay Tolerant Networking (DTN)
• DTN is a set of protocols that act together to enable a standardized method of performing store-carry-and-forward communications.
• Characteristics of DTN: i. Intermittent connectivity
– No end-to-end path between source and destination
ii. Long variable delay – Long propagation delays
between nodes
A
B
B
C
C D
Source
Store
Carry
Forward
Store
Carry
Forward
Delay Tolerant Network (DTN) = Mobile Opportunistic Network (OppNet)
Opportunistic Mobile Networks (DTN)
Store-Carry-Forward
• Opportunistic networks typically wireless • Nodes are typically handheld devices carried by people • No infrastructure required • Nodes communicate directly with each other
Why Ad Hoc Networks ?
• Setting up of fixed access points and backbone infrastructure is not always viable – Infrastructure may not be present in a disaster area or
war zone – Infrastructure may not be practical for short-range
radios; Bluetooth (range ~ 10m)
• Ad hoc networks: – Do not need backbone infrastructure support – Are easy to deploy – Useful when infrastructure is absent, destroyed or
impractical
Many Applications
• Personal area networking – cell phone, laptop, ear phone, wrist watch
• Military environments – soldiers, tanks, planes
• Civilian environments – taxi cab network – meeting rooms – sports stadiums – boats, small aircraft
• Emergency operations – search-and-rescue – policing and fire fighting
Leveraging The Power of Mobile Phones • 3.3 billion people worldwide use cell phones • Mobile phones are integrated with Wi-Fi, cameras, Bluetooth,
and others. – creates a huge number of contact opportunities
Smartphones – The Enabler
Camera GPS
WiFi
Big Storage
CPU Power
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3G
WiFi
WiFi
WiFi
3G
3G 3G Base station
OppNet in Emergency Response Scenario
Public Safety
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3G
WiFi
WiFi
WiFi
3G
3G Base Station down
X X
X X WiFi WiFi
OppNet in Emergency Response Scenario
Public Safety Smartphones (Nodes) can be carried by “Pedestrians” or “Vehicles”
Send “SOS” messages Send photos of victims or self Can we send videos? What kind of file size?
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3G
WiFi
WiFi
WiFi
3G
3G Base Station down
X X
X X WiFi WiFi
Internet
Internet
Ability to Connect to Internet at Remote Ends
Public Safety
Question: Can smartphones help us during Emergency Situation?
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3G
WiFi
WiFi
WiFi
3G
3G Base Station down
X X
X X WiFi WiFi
Internet
Internet
DTN Gateway
DTN Gateway
Challenges in Mobile Environments
· Limitations of the Wireless Network · packet loss due to transmission errors · variable capacity links · frequent disconnections/partitions · limited communication bandwidth · Broadcast nature of the communications
· Limitations Imposed by Mobility · dynamically changing topologies/routes · lack of mobility awareness by system/applications
· Limitations of the Mobile Computer · short battery lifetime · limited capacities
Other Applications of DTNs
Wildlife monitoring 1
3
2 Communication in rural villages
Emergency/military
Application Scenario – Wildlife Monitoring • ZebraNet
Do zebras in the African bush have a pattern of migration or do
they just move around in a random fashion across the year?
• A Princeton University project • Custom tracking collar with GPS (node) is put on the
neck of the zebra. • Nodes record zebra’s location and stores in memory. • Nodes carry the data until meet another node. • Exchanges data with another zebra when in
communication range. • Mobile base station (MBS) collects data from collars
when researchers are in the field. • MBS is not fixed, rather it moves and is only
intermittently available • Physical presence of the researchers is no longer
required at the deployment site in order to collect and publish zebra mobility pattern data.
• Network connectivity is intermittent and opportunistic
Application Scenario – Communication in Rural Villages • DakNet
Goal: Bring Internet connectivity to rural areas • It is aimed at providing cost-effective
connectivity to rural villages in India, where deploying a standard Internet access is not cheap.
• Kiosks are built up in villages and are equipped with digital storage and short-range wireless communications.
• Mobile Access Points (MAPs) mounted on buses, motorcycles, etc., exchange data with the kiosks wirelessly.
• MAPs may also download requested info (news, music, etc.) and bring it to villages.
• Kiosks connectivity • Dial-up - slow (28 kbps) • Short range communication
Application Scenario – Military
When M1 and M2 are both connected, data is transferred directly.
When the link between M2 and satellite is disconnected, data is transferred to HQ for storage and later delivery to M2.
Ziyi Lu and Jianhua Fan. Delay/Disruption Tolerant Network and its Application in Military Communications, International Conference On Computer Design And Applications (ICCDA 2010), 2010.
When M2 is reconnected, data stored at HQ is delivered, even if M1 is disconnected.
Soldiers need to be able to communicate with each other in the battlefield
DTN technology can be used to achieve the communication even though the end-to-end connection does not exist.
Challenges
Challenging Research in DTN/OppNet
ROUTING TRUST
C1
C6
C3
C2
C3
C5
Node Mobility
Source
Destination
Example: Disaster relief efforts, mining operations, health campaigns In emergency situations, entities with any sensing capabilities such as cellphones with GPS or desktops equipped with surveillance cameras, can be especially valuable for the OppNet.
C4
Routing Challenges
N1
N2
Mobility Pattern
Node Speed
Type of Communication
Transmission Range
Buffer Size Battery Life Time-to-Live Message Size
Routing Mechanism
Number of Nodes
Size of Area
Factors That Impact Performance
Mobility Model
Random Movement
Random Walk Random Waypoint
Mobility model
Random movement
Human behavior based movement
Map-constrained random movement
• Each mobile nodes starts at a random location and staying there for a certain period of time (pause time) and at the end of the pause time, the nodes select a random destination and move to the selected destination at a random speed.
• Each mobile nodes starts at a random location and then move to a new location by randomly choosing a direction and speed.
Map-constrained random movement
e.g. KLCC (A) to KL Pavilion (B)
• move from stop to stop using shortest paths
• nodes follow certain route (e.g. bus)
Mobility model
Random movement
Human behavior based movement
Map-constrained random movement
1
2
Random Map-Based Movement Shortest Path Map-Based Movement Routed Map-Based Movement
Can we do better?
Closing the Gap
Opportunistic Networks
Social Networks +• Close the gap between
human and network behavior
• Opportunistically follow the way humans come into contact
• Exploit human relationships
• Built more efficient and trustworthy protocols
Human, electronic, and virtual social networks. Embedding the social relationships in the electronic world identifies at least two levels in an opportunistic environment: an electronic social network (where relationships depend on the physical properties) and a virtual social network that builds an overlay atop the electronic social network.
Social Network Routing
Social Contact
The social importance of a user in facilitating the
communication among other users
Social Interest
Users with common interest are usually friends and tend to contact each other more
frequently
Social Relation
Users are formed into groups according to their social
relationship
A technique for determining the paths that data takes across networks based on social behavior patterns (social contact, interest, and relationships)
Human Behavior Based Movement
Mobility model
Random movement
Human behavior based movement
Map-constrained random movement
EKMAN, F., KER¨A NEN, A., KARVO, J., AND OTT, J. Working Day Movement Model. In Proc. 1st ACM/SIGMOBILE Workshop on Mobility Models for Networking Research (May 2008).
• Bring more reality of human movement patterns during a working day
• It produces similar Inter-contact times and contact durations as real world traces
• All nodes move on a real world map • There are three major activities:
1. Staying at home – node wake up in the morning
2. Working at the office - go to the office and works 8 hours
3. Doing some activity with friends in the evening
• Use different transportation between activities (bus, car or walking)
Working Day Movement Model (WDM)
Routing
Routing
When and where to forward data?
School bus is just coming
Jack is at school
John have a message for
Jack
This is for Mrs. Wilson
I will give the copy to everyone I meet, and hopefully it
will reach her
Concept: Floods messages into the network Goal: Maximize message delivery rate Disadvantages: • High resources usage (buffer) • High overhead
Epidemic: Epidemic Routing for Partially Connected Ad Hoc Networks
[Ref: A. Vahdat and D. Becker. Epidemic Routing for Partially Connected Ad Hoc Networks. Technical Report CS-2000-06, CS. Dept. Duke Univ., 2000.]
Epidemic
Spray and Wait
Routing protocol
Spray and Focus
Prophet
Mrs. Wilson
Concept: Use past encounters to predict future best Goal: Improve the performance of Epidemic Disadvantage: No guarantee to meet a better node in a message life time
Prophet: Probabilistic Routing Protocol using History of Past Encounters and Transitivity
This is for Mrs. Wilson
Let me do it. I will
probability meet her as
usual
[Ref: A. Lindgren, A. Doria, and O. Schelen. Probabilistic Routing in Intermittently Connected Networks. ACM Mobile Computing and Communications Review, 2003.]
0.3
S D
A
B
0.5
X
1.0
0.5
?
A or B ?
0.7
Decision based on delivery probability and transitivity (the probability for a node to encounter a destination)
Epidemic
Prophet
Routing protocol
Spray and Focus
Mrs. Wilson
Spray and Wait
Received messages with different Queue size
Prophet has higher received messages than Epidemic
Number forwarded messages with different Queue size
Prophet has lower overhead than Epidemic
100m
50m
100m
50m
Epidemic Epidemic
Prophet
Simulation parameters Simulation area: 1500 x 300 m Number of nodes: 50 Mobility model: Random Waypoint
Epidemic Prophet
Prophet
Epidemic
Prophet
Concept: Controlled flooding / Limit number of copies made Goal: to reduce the overhead of Epidemic Disadvantage: • High delay • Random Movement (If the nodes that receive a
copy of the bundle never cross paths with the destination, the system fails completely)
Spray and Wait: Efficient Routing in Intermittently Connected Mobile Networks: The Multiple-copy Case
This is for
Mrs. Wilson
I will spread four copies to first four that I meet,
and hopefully it will reach
her
Spray Phase
Source will generate and distribute a small number of copies to only a few relay
Wait Phase
Each relay carries its copy until it meets the destination and delivers it directly to the destination (each relay will forward its copy only to the destination)
Epidemic
Spray and Wait
Routing protocol
Spray and Focus
Prophet
[Ref: Spyropoulos, T., Psounis, K., and Raghavendra, C. S. Spray and Wait: An Efficient Routing Scheme for Intermittently Connected Mobile Networks. In Proc. of the ACM SIGCOMM Workshop on Delay-Tolerant Networking (WDTN) , 2005.]
Mrs. Wilson
Simulation parameters Simulation area: 200 x 200 m Number of nodes: 100, 200 Mobility model: Random Waypoint
Epidemic
Spray & Wait Spray & Wait
Epidemic
The number of transmissions for Spray and Wait are very less than Epidemic
This is for Mrs. Wilson
I will spread four copies to first four that I meet, and the four person will
forward that copies to
someone else closer to Mrs. Wilson, and
hopefully it will reach her
Spray and Focus: Efficient Mobility-assisted Routing for Heterogeneous and Correlated Mobility
Concept: Limit number of copies made / controlled flooding Goal: To reduce the delay of Spray and Wait
[Ref: T. Spyropoulos ,and K. Psounis. Spray and Focus: Efficient Mobility-assisted Routing for Heterogeneous and Correlated Mobility. Proc. of IEEE Percom International Workshop on Intermittently Connected Mobile Ad Hoc Networks, March 2007.]
Source will generate and distribute a small number of copies to only a few relay
Each relay will forward its copy to another relay (the selection of relay is based on single-copy utility based scheme)
Spray Phase Focus Phase
Epidemic
Spray and Wait
Routing protocol
Spray and Focus
Prophet
Mrs. Wilson
[Ref: Jianwei Niu, Jinkai Guo, Qingsong Cai, Norman Sadeh, and Shaohui Guo. Predict and Spread: an Efficcient Routing Algorithm for Opportunistic Networking. Proc. of IEEE Wireless Communications and Networking Conference (WCNC), March 2011.]
When the value of TTL increases, the delivery latency decreases Spray and Focus has lower delivery latency than Spray and Wait
Spray&Wait
Spray&Focus
When the value of TTL increases , the delivery ratio increase Spray and Focus seem to perform slightly better than Spray and Wait in term of delivery ratio
Spray&Wait
Spray&Focus
Simulation parameters Simulation area: 4500 x 3400 m Number of nodes: 300 Transmit range: 10 m Transmit speed: 250 Kbyte/s Mobility model: Map Route Movement
MaxProp: Routing for Vehicle-Based Disruption-Tolerant Networks
[Ref: J. Burgess, B. Gallagher, D. Jensen, and B. Levine. MaxProp: Routing for Vehicle-Based Disruption-Tolerant Networks. Proc. of the 25th INFOCOM, 2006.]
This is for Mrs. Wilson
My packets are full, and I
had the message long enough, and I
am sure someone else
gave the message to
her
Concept: Packet Dropping Policy (schedule packets transmission to its peers and determines which packets should be deleted when buffer space is almost full. Packets are schedule based on encounter history of nodes throughout the network) Goal: To increase the delivery rate and lower latency Disadvantage: High processing cost in large scale networks
Epidemic
Prophet
Spray and Wait
Routing protocol
Spray and Focus
MaxProp
S
D
C1
C2
C1
C3
Node Mobility
Source
Destination
Can Opportunistic Network support Emergency Scenario?
Example: Disaster relief efforts, mining operations, health campaigns
In emergency situations, entities with any sensing capabilities such as cellphones with GPS or desktops equipped with surveillance cameras, can be especially valuable for the OppNet.
Performance Evaluation of Binary Spray and Wait OppNet Protocol in the Context of Emergency Scenario
Mazlan Abbas, Nur Husna and Norsheila Fisal
PerNEM 2013 In Cooperation with the 3rd International Workshop on IEEE PerCom 2013
Pervasive Networks for Emergency Management March 22, 2013, San Diego, California, USA
[Note: Check Results in Slideshare - http://www.slideshare.net/mazlan1/per-nem-2013-slideshare ]
Future Applications of DTN (OppNet)
OpportunisMc Network
Weather Monitoring
Water Infrastructure
Control
Public Surveillance Camera
Abandon their normal daily functions…… and become “helpers”
Help to sense fires and flooding
Help to sense vehicular movement and traffic jams
Help to search for images of human victims
During Disaster…. Benevolent OppNet scenario – “Citizens called to arms”
OpportunisMc Network
Weather Monitoring
Water Infrastructure
Control
Public Surveillance Camera
Recruit “helpers” to analyze wind patters that can contribute to a faster spread of poisonous chemicals.
Help to sense wind patterns
Help to sense vehicular movement and traffic jams
Help to locate police and military personnel
Before City Siege …. Malevolent OppNet scenario – “Bad guys gang up”
Give it to me, I have 1G bytes phone flash.
I have 100M bytes of data, who can carry for me?
I can also carry for you!
Thank you but you are in the opposite direction!
Don’t give to me! I am running out of storage.
Reach an access point.
Internet
Finally, it arrive…
Search Roar.mp3 for me
Search Roar.mp3 for me
Search Roar.mp3 for me There is
one in my pocket…
Consumer Applications
Hi what’s up?
There is a mega sale!!
Cool.. I m gonna tell my friend!! Thanks buddy
Shopping Malls
Terminal Bus A
Terminal Bus B Terminal Bus C
Terminal Bus D
Synchronize with “local contents”
Smart Transportation
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Summary
• Opportunistic Networks (OppNets) are very useful in the context of emergency scenarios
• We discovered that Binary Spray and Wait Protocol is one good option for routing
• Smartphones seems to be a good potential candidate communications tool in emergency scenarios
• Speedier nodes (vehicles) require smaller Message size (images rather than videos).
Future Work
• Requires actual datasets (emergency scenarios) for mobility model
• Mixed mobility scenarios (pedestrians plus vehicles) • Find better battery efficient methods • Further refinements to Spray & Wait Protocol with
other parameters such as Contact Time etc. • Implementation on smartphones – e.g. WiFi Direct
802.11ac or Bluetooth
EMAIL: [email protected] LINKEDIN: my.linkedin.com/in/mazlan/ TWITTER: mazlan_abbas SLIDESHARE: www.slideshare.net/mazlan1 FACEBOOK: www.facebook.com/drmazlanabbas