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Routing Mechanisms in Ad-Hoc Networks

Routing Mechanisms in Ad-Hoc Networks. Mentor: Dr. Stephan Rupp Student: Wenbo Fu. Ad-hoc Network. Definition: Ad hoc network is a collection of wireless nodes that can dynamically be set up anywhere and anytime without using any pre-existing network infrastructure . .

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Routing Mechanisms in Ad-Hoc Networks

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  1. Routing Mechanisms in Ad-Hoc Networks Mentor: Dr. Stephan Rupp Student: Wenbo Fu Advanced Communication Services

  2. Ad-hoc Network • Definition:Ad 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 Advanced Communication Services

  3. 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 Advanced Communication Services

  4. Source node S E F B M L J C A G H D K I N Destination node How to find a route in Ad hoc Network? Advanced Communication Services

  5. Agenda • Overview of Ad-Hoc Network Routing Protocol • Proactive Ad-Hoc Routing Protocols (Link-State) • Reactive Ad-Hoc Routing Protocols • Conclusions Advanced Communication Services

  6. Unicast-Routing Protocol for MANET (Topology-based) Table-Driven/ Proactive Hybrid On-Demand-driven/Reactive Clusterbased/ Hierarchical Distance- Vector Link- State ZRP DSR AODV TORA LANMAR CEDAR DSDV OLSR TBRPF FSR STAR MANET: Mobile Ad hoc Network (IETF working group) Classification of Routing Protocols for MANET(Topology based) Advanced Communication Services

  7. 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. Advanced Communication Services

  8. 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 Advanced Communication Services

  9. Agenda • Overview of Ad-Hoc Network Routing Protocol • Proactive Ad-Hoc Routing Protocols (Link-State) • Reactive Ad-Hoc Routing Protocols • Conclusions Advanced Communication Services

  10. Link-State Routing Await messages Update local Topology table Update local relevant Association tables Update routing table Update routing table Forwarding Topology message Forwarding Association message Await Association timer Await Hello timer Await Topology timer TTopology TAssociation THello Topology Messages Hello Messages Own Hello Message Own Topology Message Own Association Messages Reset (TAssociation) Reset (THello) Reset (TTopology) Association Messages Await messages Update local Link -State relevant tables Advanced Communication Services

  11. Overhead of Link-State Protocols • Message generation - What, Who, When • Message processing - Local tablesupdating - Route computation • Message forwarding - Who • Goal: Decrease unnecessary overhead. Advanced Communication Services

  12. S P M Z X Y B A D OLSR (Optimized Link State Routing Protocol) - MPR (Multipoint relays)- MPR selector- Symmetric 1-hop neighbours- Symmetric strict 2-hop neighbours Advanced Communication Services

  13. ... C D ... RT-D RT-C S B U A V O E Q P F G I H T Z L J K R ... ... ... ... ... ... N M RT-A RT-B TBRPF (Topology Dissemination Based on Reverse-Path Forwarding) • Reported Nodes set (RN) • Reported Tree (RT) • Local links • Dijkstra’s algorithm Advanced Communication Services

  14. Proactive Protocol OLSR TBRPF Critical nodes Multipoint relays (MPR) Reported Node set Hello messages what All local link-state All local changed link-state Who generate the messages Any nodes Any nodes when Every Hello-interval Every Hello-interval who forwards the messages No forwarding No forwarding Topology messages what Local MPR-MPR selector links Any links in reported tree (RT) Any changed links in RT Who generate the messages MPR Any nodes when Topology-Control Interval Per-update-interval Diff-update-interval who forwards the messages MPR No forwarding Local tables Local link-state relevant tables Link set, neighbor set, MPR set, MPR selector set Only link and neighbor set Topology tables All MPR-MPR selector links in the network The topology of the whole network Route computation Route calculate Route consisting of neighbor and MPR-MPR selector links Dijkstra’s algorithm Link Metric Hops Hops or other metrics Link status Symmetric (bidirectional) Symmetric (2 - way) Destination network Large, dense mobile network Up to a few hundred nodes network Comparison between OLSR and TBRPF Advanced Communication Services

  15. Agenda • Overview of Ad-Hoc Network Routing Protocol • Proactive Ad-Hoc Routing Protocols (Link-State) • Reactive Ad-Hoc Routing Protocols • Conclusions Advanced Communication Services

  16. Source node S Intermediate node i -1 Intermediate node i Intermediate node i + 1 Destination node D Route Request Route Request Route Request Route Request Route discovery 1 Route Reply Route Reply Route Reply Route Reply Data forwarding Data forwarding Route maintenance Route Error Route Error Route Request Route Request Route discovery 2 Route Reply Route Reply Procedure Diagram of Reactive Protocols Advanced Communication Services

  17. 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. Advanced Communication Services

  18. Backward path to S D-CBA-S Forward path to D S-ABC-D S1-A1BC-D1 S A B C D S1 A1 D1 AODV (Ad hoc On-Demand Distance Vector) • Intermediate nodes- Backward and forward path.- Precursor list • Expanding ring search (TTL) Advanced Communication Services

  19. S Source node E F B M L J C A G H D K I N Destination node S caches two path to D: S, E, F, J, D or S, C, G ,K, D DSR ( Dynamic Source Routing) • Muliple path- Load balance- Packet salvaging Advanced Communication Services

  20. Reactive protocols AODV DSR Route method (1) The next hop routing Source routing Route maintained in Route table Route cache Route entry (1) The next hop and the Precursors on the route to the destination Complete route to the destination Hop limit (1) Expanding ring search Expanding ring search Route metric Freshest & shortest path Shortest path Link state (1) Bi-directional Bi-directional/ unidirectional Route reconfiguration Erase Route; notify sources Erase Route; notify sources Multiple route possibilities No Yes Comparison between AODV and DSR Advanced Communication Services

  21. Agenda • Overview of Ad-Hoc Network Routing Protocol • Proactive Ad-Hoc Routing Protocols (Link-State) • Reactive Ad-Hoc Routing Protocols • Conclusions Advanced Communication Services

  22. 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. Advanced Communication Services

  23. Acknowledgements • Dr. Stephan Rupp • Prof. Paul J. Kuehn • Miss Napat Nantavechsanti • Mr. Thomas Buergstein Advanced Communication Services

  24. Q & A Advanced Communication Services

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