1 / 24

Location-Aided Routing (LAR) in Mobile Ad Hoc Networks

Location-Aided Routing (LAR) in Mobile Ad Hoc Networks. Young-Bae Ko and Nitin H. Vaidya Yu-Ta Chen 2006 Advanced Wireless Network. C. S. A. D. X. B. E. Basic Idea. Route discovery using flooding algorithm:. Basic Idea (cont.). Location information Minimize the search zone

Download Presentation

Location-Aided Routing (LAR) in Mobile Ad Hoc Networks

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript


  1. Location-Aided Routing (LAR) in Mobile Ad Hoc Networks Young-Bae Ko and Nitin H. Vaidya Yu-Ta Chen 2006 Advanced Wireless Network

  2. C S A D X B E Basic Idea • Route discovery using flooding algorithm:

  3. Basic Idea (cont.) • Location information • Minimize the search zone • Reduce the number of routing messages • Speed and direction information • More minimization of the search zone • Increases the probability to find a node

  4. Basic Idea (cont.) • Each node knows its current location • Using last known location information and average speed for route discovery • Limited destination zone – expected zone • Restricted flooding – request zone • Route discovery is initiated when • Source does not know a route to destination • Previous route from source to destination is broken

  5. Definitions • Expected zone • S knows the location of D at time t0 • Current time is t1 • The location of D at t1 is the expected zone

  6. Direction information: moving toward north No direction information Expected Zone

  7. Definitions (cont.) • Request zone • S defines a request zone for the route request • The request zone includes expected zone • The route request messages only flood in request zone • If S can not find a route within the timeout interval, create a expanded request zone

  8. Request Zone

  9. LAR Scheme 1 • The request zone is the smallest rectangle to include the expected zone and the location of source • S Includes the coordinates of corners and location of D(t0) in routing messages • The node outside the rectangle should not forward route message to neighbors • When D receives the message, it replies a route reply message including its current location and current time • When S receives the route reply message, it records the location of node D.

  10. A (Xs, Yd+R) B (Xd+R, Yd+R) Expected zone R Request zone D (Xd, Yd) J (Xj, Yj) I (Xi, Yi) D (Xd+R, Ys) S (Xs, Ys) Network Space Source node outside the expected zone LAR Scheme 1 (example)

  11. A (Xd-R, Yd+R) B (Xd+R, Yd+R) Expected zone S (Xs, Ys) R (Xd, Yd) D Request zone D (Xd+R, Yd-R) C (Xd-R, Yd-R) Network Space Source node within the expected zone LAR Scheme 1 (example)

  12. LAR Scheme 2 • The distance between S and D is DISTs • S includes DISTs and (Xd, Yd) in route request message • When node I receives route request • Calculates its distance to D (DISTi) • If DISTs+δ DISTi then forwards the request and replace DISTs by DISTi • Otherwise, node I discards the route request • δ is a parameter for increasing the probability of finding a route or dealing with location error • The request is forwarded closer and closer to destination D

  13. D (Xd, Yd) DISTs DISTn DISTi N DISTk I K S (Xs, Ys) Network Space Parameter δ= 0 LAR Scheme 2 (example)

  14. Error in Location Estimate • Impact of location error • GPS may include some error • With a larger location error, the size of request zone increases • Usually location error contributes to an increase in routing overhead • But routing overhead may decrease with increasing error, why? • In LAR scheme 1, radius of expected zone = e + v(t1 – t0), e is location error • In LAR scheme 2, there is no modification

  15. Different average speed of nodes Percentage of Improvement # of Routing packets per Data packet Simulation Result

  16. Different transmission range of nodes # of Routing packets per Data packet # of Routing packets per Data packet Simulation Result (cont.)

  17. Different number of nodes in network # of Routing packets per Data packet # of Routing packets per Data packet Simulation Result (cont.)

  18. Different location error Percentage of Improvement # of Routing packets per Data packet Simulation Result (cont.) Location Error (units) Location Error (units)

  19. Simulation Result (cont.) • LAR perform better in various speed • Especially in high speed • LAR perform better in various transmission range • Exception: very low transmission rate • LAR perform better in various amount of nodes • Exception: small amount of nodes

  20. Expected Zone D Original Request Zone S Alternative Request Zone Variations and Optimizations • Alternative definition of request zone in LAR scheme 1

  21. Variations and Optimizations (cont.) • Adaptation of request zone • If an intermediate node I holds a more recent location information of D, it can update the request zone Adapted Request Zone as per node I D J Adapted Request Zone as per node J Initial Request Zone I S

  22. Variations and Optimizations (cont.) • Adaptation of request zone • Even though LAR scheme 2 does not explicitly define request zone, the zone that the source node ask can be seen as a circular zone D DISTs DISTi I S

  23. Variations and Optimizations (cont.) • Local search • Allow any intermediate node I detecting route error to initiate a route discovery • Node I uses a request zone based on its own location information for node D D D I I S S Request Zone determined by S Request Zone determined by I

  24. Conclusion • Location information significantly lower routing overhead • Various optimizations can be done to adjust LAR to a certain network

More Related