Routing Mechanisms in Ad-Hoc Networks

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Routing Mechanisms in Ad-Hoc Networks

• Mentor Dr. Stephan Rupp
• Student Wenbo Fu

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Ad-hoc Network

• DefinitionAd hoc network is a collection of
  wireless nodes that can dynamically be set up
  anywhere and anytime without using any
  pre-existing network infrastructure.

• Application- Military battlefield.
• - Disaster field
• - Conference
• - Sensor Dust

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Characteristics of Ad hoc Network

• Ad hoc Network is a mobile, mutlihop, wireless
  network with autonomous terminals.

- Dynamic topologies - Bandwidth-constrained -
Energy-constrained operation - Limited physical
security
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How to find a route in Ad hoc Network?
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Agenda

• Overview of Ad-Hoc Network Routing Protocol
• Proactive Ad-Hoc Routing Protocols (Link-State)
• Reactive Ad-Hoc Routing Protocols
• Conclusions

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Classification of Routing Protocols for MANET
(Topology based)
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Proactive vs Reactive Routing Protocols

• Proactive routing protocols (table-driven
  protocols) attempt to maintain consistent, up to
  date routes from each node to every other nodes
  in the network.
• Reactive routing protocols (on-demand driven
  protocols) create routes only when desired by the
  source node.

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Proactive vs Reactive Routing Protocols

• Proactive Routing Protocols
• Routes to all reachable nodes in the network
  available.
• Minimal initial delay for application.
• - Larger signalling traffic and power
  consumption.
• Reactive Routing Protocols
• Smaller signalling traffic and power
  consumption.
• - A long delay for application when no route to
  the destination available

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Agenda

• Overview of Ad-Hoc Network Routing Protocol
• Proactive Ad-Hoc Routing Protocols (Link-State)
• Reactive Ad-Hoc Routing Protocols
• Conclusions

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Update local Link -State relevant tables
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Overhead of Link-State Protocols

• Message generation
• - What, Who, When
• Message processing
• - Local tables updating
• - Route computation
• Message forwarding
• - Who
• Goal Decrease unnecessary overhead.

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OLSR (Optimized Link State Routing Protocol)

• - MPR (Multipoint relays)- MPR selector-
  Symmetric 1-hop neighbours- Symmetric strict
  2-hop neighbours

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TBRPF (Topology Dissemination Based on
Reverse-Path Forwarding)

• Reported Nodes set (RN)
• Reported Tree (RT)
• Local links
• Dijkstras algorithm

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Comparison between OLSR and TBRPF
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Agenda

• Overview of Ad-Hoc Network Routing Protocol
• Proactive Ad-Hoc Routing Protocols (Link-State)
• Reactive Ad-Hoc Routing Protocols
• Conclusions

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Procedure Diagram of Reactive Protocols
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Overhead of Reactive Protocols

• Route discovery
• - Information maintained in intermediate nodes
• - Information contained or hidden in messages
• - Length of flooding
• Route maintenance
• - How to find an alternative route
• - How to inform influenced nodes
• Goal Minimize application delay and decrease
  unnecessary overhead.

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AODV (Ad hoc On-Demand Distance Vector)

• Intermediate nodes - Backward and forward
  path.- Precursor list

• Expanding ring search (TTL)

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DSR ( Dynamic Source Routing)

• Muliple path- Load balance- Packet salvaging

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Comparison between AODV and DSR
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Agenda

• Overview of Ad-Hoc Network Routing Protocol
• Proactive Ad-Hoc Routing Protocols (Link-State)
• Reactive Ad-Hoc Routing Protocols
• Conclusions

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Conclusions

• Four candidates for standard protocols of IETF
  with different features.
• Algotithms are continuously modified and
  improved.
• Feasibility still needs to be tested in practice.
• No clear winners among specification.
• Issues such as security and interworking should
  be emphasized in future.

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Acknowledgements

• Dr. Stephan Rupp
• Prof. Paul J. Kuehn
• Miss Napat Nantavechsanti
• Mr. Thomas Buergstein

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• Q A