ROUTING IN WIRELESS SENSOR NETWORKS By: Syed Ashar Zia Elet-6316: Routing Algorithms & Protocols Dr. Driss Benhaddou
Jun 09, 2015
ROUTING IN WIRELESS SENSOR
NETWORKS
By: Syed Ashar Zia
Elet-6316: Routing Algorithms & ProtocolsDr. Driss Benhaddou
BY: SYED ASHAR ZIA 2
About Presentation Phase I: Introduction to Wireless
sensor networks, its applications, architecture, and challenges.
Phase II: Routing Protocols introduction, DSDV, AODV, Cluster-based routing.
Phase III: Performance evaluation of AODV and DSDV through simulation.
PHASE - I:INTRODUCTION TO WIRELESS SENSOR
NETWORKS
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WSN Introduction
WSN refers to a network of sensor nodes connected through wireless medium.
WSN is usually a large network connecting even more than a thousand nodes.
Sensor nodes are used to monitor, record and notify specific conditions at various locations.
Conditions could be temperature, humidity, wind, pressure, and many more.
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WSN: Applications
WSN has a wide range of applications, such as:Military applications,Environmental monitoring,Industrial sensing,Security applications.
WSN is very useful for monitoring remote locations where human access is limited or not possible at all.
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WSN Architecture
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WSN Architecture
Fig: Sensor Network with Internet access
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Components of WSN
Sensor nodes/End nodesResponsible for sensing the conditions.
Base Station/Sink nodeCollects information from end-nodes.
Gateways Processing Hub
Processes the collected data at BS. Storage Hub
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Different Tiers in WSN
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Protocol Stack in WSN Three layers are
added in TCP/IP model.
To increase the awareness at the nodes.
Task, Mobility & Power are crucial information in sensor networks.
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Challenges in WSN
ArchitectureEnergy efficient architecture is priority.Compromises could be made on size,
capacity, cost & speed.
RoutingDifferent from the traditional IP
Networks.Talking to thousands of nodes makes it
complex and inefficient at the energy & storage level.
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Challenges in WSN
Distributed Signal ProcessingImportant part at the low-level layer in
WSN.Provides BS with locations & signal
identification of nodes, etc.
Storage & Data retrievalCentral storage of data from several
nodes. Storage at nodes requires processing at
the nodes.
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Challenges in WSN
ActuationRequired action for sensed quantity.Such as pointing cameras, alarming
sounds, opening valves, etc.
SecurityAttackers may change the behavior of
nodes leading to change in results. Confidentiality, integrity, robustness,
and authenticity matters in WSN.
PHASE - II:ROUTING PROTOCOLS IN
WIRELESS SENSOR NETWORKS
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Routing in WSN
Routing in WSN
Network Structure
Flat Networks
Hierarchical Networks
Location based
Protocol Operation
Negotiation based
Multi-path based QoS based Query
based
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Routing in WSN
WSNs are usually ad-hoc in nature. Nodes’ communication directly to
BS defines their MANET (Mobile Ad-hoc Network) nature.
Set of standards are defined for the protocols used in Ad-hoc networks
Mobility of nodes disturbs the standards, therefore routing is quiet challenging.
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MANET Routing Standards
Routing Protocols for
MANET
Proactive/Table Driven
DSDV, FSR, STAR
Hybrid ZRP
Reactive/On-demand
Driven
DSR, AODV, TORA
Cluster-based
LANMAR, CEDAR
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MANET Routing Standards Pro-Active Protocols
Routing table with all paths maintained at each node.
E.g. DSDV (Direct Sequenced Distance Vector)
Reactive ProtocolsDiscovers route when required. E.g. AODV (Ad-hoc On-demand
Distance Vector) Hybrid
Combination of Proactive & Reactive protocols.
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Distance Vector Routing Each node maintains a routing table
containingList of all available destinationsNumber distance to each each destinationNext hop to reach a destination
The succession of next hops leads to a destination
Each node periodically broadcasts its current estimate of the shortest distance to each available destination to all of its neighbors
Typical representative: Distributed Bellman-Ford
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Bellman-Ford Algorithm
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Direct Sequenced DV Design Goals
Keeping the simplicity of Bellman-Ford.Avoid looping issues
Route information is transmitted by broadcast
Updates are transmitted periodically or immediately when any significant topology change is availableEven sequence no.s are assigned by destinationIf a broken link is detected: metric ∞ and
updated odd sequence no. are assigned by detecting host.
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Direct Sequenced DV
Types of Broadcast updatesFull Dump:All information from the
transmitting node.Incremental: All information that has
changed since the last full dump.
Full dump is transmitted if incremental dump exceeds the size of one NPDU.
Routing Table is maintained with latest sequence numbered route and least cost metric.
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Advantages: DSDV
Excellent performance in small networks.
Energy efficient as route processing is minimal.
Routing overhead is approximately constant regardless of node movements and traffic load.
Simple implementation using Bellman-Ford algorithm.
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Disadvantages: DSDV
Bandwidth and size of table increases with increasing number of nodes.
Overhead increases for maintaining large no. of nodes, hence degrades the performance of network.
Fails to converge if nodes are changing locations quickly.
Not very efficient in route updating. Limits no. of nodes that can join
network.
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Ad-hoc On-demand DV Intended for the networks with
thousands of nodes. It’s a reactive or demand-driven protocol
which calculates the route when required and caches it for further use.
Routing table only maintains next hop for the destination rather than complete route.
Freshness of route is maintained by sequence numbers.
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Ad-hoc On-demand DV
Routing Table maintains:Destination IP addressDestination sequence numberValid destination sequence number
flagOther state & routing flagsNetwork interfaceHop countNext hopLifetime (route expiration time)
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Ad-hoc On-demand DV Basic message
set in AODV includes:Hello - For link
statusRREQ - Route
RequestRREP - Route ReplyRERR - Route Error
Only in case of Route is not in table and has to be discovered.
B?
B? B
?B
?
B?
B?
B?
B
ARREQ Message
B
A
A
A
A
A
A
A
RREP Message
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Ad-hoc On-demand DV
Maintenance of Routes is handled very efficiently in AODVHello messages broadcast by active nodes
periodically called HELLO_INTERVAL.If no Hello reply from a neighbor within
DELETE_PERIOD link failure is identified.RERR message is broadcasted to other
neighbors.Entries based on that node invalidated.Route is rediscovered using RREQ when it is
required.
PHASE - III:PERFORMANCE ANALYSIS
DSDV & AODV
Simulation done by:Abdul Hadi Abd Rahman & Zuriati Ahmad ZukarnainEuropean Journal of Scientific Research
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AODV vs DSDV
In AODV graph fluctuates between 0.3 and 2.4sec while in DSDV it is between 0.005 and 0.008 sec. This shows that route calculation or discovery method in AODV increases the End-to-End delay.
Scenario 1: End-to-End Delay with increasing number of nodes.
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AODV vs DSDV
Here, three routing protocols are compared, AODV, DSDV and Improved DSDV. Here, we can see that with increasing no. of nodes routing overhead increases dramatically in DSDV which causes instability when it’s a large network.
Scenario 2: Routing Overhead with increasing number of nodes.
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ANALYSIS RESULTS
Small WSN:DSDV is better than AODV.Less routing overheadDelay is negligible when compared to
the time it takes to calculate route in AODV.
Large WSN:AODV is better than DSDVEfficiently handles mobility and route
updates.Less overhead and appropriate delay.
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REFERENCES Routing in Wireless sensor networks – Rachid
Ennaji & Muhammad Boulmalf – IEEE, 2009 Performance comparison of AODV, DSDV and I-
DSDV – Abdul Hadi & Zuriati Ahmed – European Journal of Sc. Research
Group-based clustering RP – Lei Zhang – IEEE, 2007
http://www.ece.ul.ie/homepage/tom_newe/RFP05.html
http://www.ece.gatech.edu/research/labs/bwn/WMSN/projectdescription.html
www.authorstream.com
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QUESTIONS?