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Consistent Route Optimization Mechanism (CROM) for AODV in MANETs

Consistent Route Optimization Mechanism (CROM) for AODV in MANETs. 고려대학교 박사과정 2 학기 이 기원 2011. 12. 08. Contents. Introduction Motivation Background Shrink Consistent Route Optimization Mechanism Conclusion. Introduction (1/2). Many routing protocols have been proposed

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Consistent Route Optimization Mechanism (CROM) for AODV in MANETs

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  1. Consistent Route Optimization Mechanism (CROM) for AODV in MANETs 고려대학교 박사과정 2학기 이 기원 2011. 12. 08

  2. Contents • Introduction • Motivation • Background • Shrink • Consistent Route Optimization Mechanism • Conclusion

  3. Introduction (1/2) • Many routing protocols have been proposed • different network structures, mobility scenarios and types of applications. • Routing algorithm for MANETs, • must consider is the behavior of the proposed algorithm in the presence of node movement • Mobility has a potential to result in dynamic changes to network topology, making the task of routing algorithms more difficult

  4. Introduction (2/2) • Two major challenges introduced by mobility • disconnection • sub-optimality in connection routes • If the network topology is dynamically changing due to node movement, at least one of the following two events eventually occurs: • (i) connection breaks because one of its constituent links becomes disconnected • (ii) route becomes sub-optimal due to changes in the network topology

  5. Motivation → Formation of a non-optimal route • Reactive routing protocols generally take care of the disconnectionevent by initiating local recovery or restarting the route discovery process • The sub-optimalityevent is not often considered, and accordingly is the focus of this paper • (i) reduces the end-to-end delay • (ii) increases spatial reuse and network capacity • (iii) makes the connection more resilient to breakages

  6. Shrink mechanism (1/3)

  7. Shrink mechanism (2/3) • When an intermediate node (e.g. node C) receives a Shrink-0 packet from the previous hop (e.g. node B), it produces two Shrink packets • Shrink-0 message is sent to the next hop (in the example, node D) along the path towards the destination • The IP address of the previous node • The IP address of the sender (i.e. node S in this case) • The IP address of the final destination (i.e. node T) • Shrink-1, on the other hand, is sent to the upstream node two hops away (i.e. node A)

  8. Shrink mechanism (3/3) • Elimination of the unnecessary hops: • when a node receives Shrink-1 packet from another node, there may be a short cut available between this node and the sender of Shrink-1 message • Shrink detects the shortcuts only between the nodes which are located 2-hop away to each other

  9. Consistent route optimization mechanism • Consistent route optimization mechanism (CROM) • eliminates the unnecessary hops in an active route • becomes active after a route between a source-destination pair has been constructed by the routing protocol • Reduce a multi-hop connection to 1-hop connection by eliminating an unnecessary relay node! • exploits the broadcast feature of wireless transmissions

  10. CROM (1/3) • Route discovery stage • when the route is needed, the source sends the RREQ packet in a controlled flooding manner throughout the network • intermediate node checks its routing table • If with the routing information, reply to destination with the RREP packet • otherwise, the intermediate forwards RREQ packet to its neighbors • finally, the destination or some intermediate nodes will reply the routes to the source

  11. CROM (2/3) • Route maintenance stage • intermittent nodes cache the RREP packet with the routing information • cache replacement policy • frequency of route usage • elapsed time since route usage • if an intermediate node overhear packet from the upstream n-hops in RREP route and received signal strength is over the threshold S • it sends data packet to next hop • it sends CROM packet to upstream n-hops away

  12. CROM (3/3) • CROM packet • considered as revised RREP • contain route to CROM destination to CROM sender • when a node receives CROM packet , it updates the routing table based on RREP information in CROM packet • it can detect the shortcuts n-hop away to each other

  13. cache cache cache RREP cache RREP N8 N2 N5 N9 RREP RREP N1 N7 RREP N4 N3 N6

  14. N5 N8 DATA N2 Overhear DATA DATA N7 N1 N9 N4 N3 N6

  15. N5 CROM CROM N8 N2 CROM N7 DATA N1 N9 N4 N3 N6

  16. Conclusion • This paper propose and evaluate an extension to AODV which makes use of continuous route optimization through CROM packet • performs well with respect to routing overhead incurred, while serving to minimize path stretch relative to optimality

  17. Reference [1] Z. Bilgin and B. Khan “A Dynamic Route Optimization Mechanism for AODV in MANETs,” IEEE ICC, Capetown ,2010 [2] S. Park and B. Voorst, “Anticipated Route Maintenance (ARM) in Location-Aided Mobile Ad Hoc Networks.” Globecom, San Antonio, USA, 2001.

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