CS 218Lecture

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CS 218-Lecture 3 Extensions of Ad Hoc on
Demand Routing/multicast

• Clustering (to reduce redundant floods)
• Mobility predicition
• Load balancing
• Back up route planning
• reliable ad hoc multicast
• joint uni and multicast?

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On Demand Routing in Large Ad Hoc Wireless
Networks With Passive Clustering
Mario Gerla, Taek Jin Kwon and Guangyu
Pei Computer Science Department University of
California, Los Angeles Los Angeles, CA, 90095
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Readings for Lecture 3 ad hoc routing
extensions

• Please find the papers below on CS 218 web page
  or on NRL web page
• K. Tang and M. Gerla, "Reliable on-demand
  multicast routing with congestion control in
  wireless ad hoc networks,In Proceedings of SPIE
  2001, Denver, Colorado, August 2001.
• M. Gerla, T. J. Kwon, and G. Pei, "On Demand
  Routing in Large Ad Hoc Wireless Networks with
  Passive Clustering," In Proceedings of IEEE WCNC
  2000, Chicago, IL, Sep. 2000.
• AODV-BR Backup Routing in Ad hoc NetworksS.-J.
  Lee and M. GerlaProceedings of IEEE WCNC 2000,
  Chicago, IL, Sep. 2000.
• Mobility Prediction in Wireless NetworksW. Su,
  S.-J. Lee, and M. GerlaProceedings of IEEE
  MILCOM 2000, Los Angeles, CA, Oct. 2000.

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Readings for Lecture 3 ad hoc routing
extensions (cont)

• Dynamic Load-Aware Routing in Ad hoc
  NetworksS.J. Lee and M. Gerla. Proceedings of
  ICC 2001, Helsinki, Finland, June 2001.
• Exploiting the Unicast Functionality of the
  On-Demand Multicast Routing ProtocolS.-J. Lee,
  W. Su, and M. GerlaProceedings of IEEE WCNC
  2000, Chicago, IL, Sep. 2000.

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Clustering in Ad hoc Networks

• A natural way to provide some structure in an
  ad hoc network
• Better Channel Efficiency(code diversity)
• Bandwidth allocation QoS support
• Cluster based routing - scalability
• Suppress redundant transmissions in On-Demand
  Routing

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Example of Clustering
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AODV flooding O/H

• AODV requires flood-search to find and establish
  routes
• Flood-search each node forwards Query pkt (RREQ)
  to neighbors
• If network is dense (ie, several nodes within
  the tx range), this leads to a lot of redundant
  transmissions
• Energy waste throughput loss

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Clustering helps On-demand routing

• The network is organized in clusters
• All nodes in a cluster can communicate directly
  (one hop) with clusterhead
• Gateways maintain communications between clusters
• Only clusterheads and gateways forward
  search-flood queries
• Suppress redundant transmissions!

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Example of Clustehead Gateway Forwarding
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Drawbacks of Conventional Clustering (eg,Least ID
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• Periodic neighbor connectivity monitoring may
  lead to high O/H
• Periodic control traffic not desirable in
  military covert operations
• Unstable behavior of least ID cluster election
  scheme small move - large change!

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Passive Clustering

• Goals no monitoring O/H, more stable..
• Approach
• (a) No Active Control Packets Cluster state
  information piggybacked on data packets
• (b) Clusters are built only when on-demand routes
  are opened
• (c) Soft state when data transmissions cease,
  time-out clears stale clusters

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Passive Clustering (cont)

• Election First Declaration Wins (FDW)
  Whichever node claims the CH role first, gets
  it
• Improved Stability
• No chain reaction effect, no rule to enforce (eg,
  Lowest ID)
• Can work with only partial neighbor info.
• Not everybody has to talk (as in conventional
  clustering schemes)
• Very energy efficient in dense networks

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Passive Clustering example
Assume Node 1 initiates a search flood.
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Passive Clustering
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Passive Clustering
Clusterhead_ready
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Passive Clustering
Clusterhead
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Passive Clustering
Ordinary Node
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Passive Clustering
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Passive Clustering
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Passive Clustering
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Passive Clustering
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Passive Clustering
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Passive Clustering
Gateway
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Passive Clustering
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Passive Clustering
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Passive Clustering
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Passive Clustering
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Passive Clustering
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Passive Clustering
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Passive Clustering
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Passive Clustering
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Passive Clustering
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Passive Clustering
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Passive Clustering
Resulting cluster structure.
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Lowest ID Clustering result
3 isolated clouds 1, 2, and the rest
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Simulation Environment (GloMoSim)

• 100 nodes in 1000m x 1000m
• Transmission range 150m
• Mobility model Random Waypoint
• AODV unicast routing
• Random Source/Destination Pairs
• CBR traffic.
• 512 bytes per packet, 0.4 packets per sec

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Normalized Routing Overhead
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Normalized Routing Overhead
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Mean End-to-End Delay
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Mean End-to-End Delay
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Throughput
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Throughput
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Summary

• Passive clustering
• Realistic, overhead free mechanism
• First Declaration Wins rule
• Stable clusterhead election
• AODV application
• Efficient search-flood higher thoughput
• Next try Passive Clustering on DSR, ODMRP and
  other search-flood schemes