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

19

3G

WiFi

WiFi

WiFi

3G

3G 3G Base station

OppNet in Emergency Response Scenario

Public Safety

20

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?

21

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?

22

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

57

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: mazlan@gmail.com LINKEDIN: my.linkedin.com/in/mazlan/ TWITTER: mazlan_abbas SLIDESHARE: www.slideshare.net/mazlan1 FACEBOOK: www.facebook.com/drmazlanabbas