92846 CSCI696501 Special Topics on WIRELESS AD HOC NETWORKS

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92846 CSCI-6965-01 Special Topics on WIRELESS
AD HOC NETWORKS

• S. Yang

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Introduction to Wireless Ad Hoc Networks
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Research Model
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Connected Dominating Set (CDS)

• Virtual network backbone
• Energy efficiency / interference reduction
• A node set is the DS if every node is
• in the set, or
• has at least one neighbor in the set
• If all nodes in the DS is connected, the set is a
  CDS

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Connected Dominating Set (CDS)

• CDS as a virtual backbone
• Domination
• Connectivity
• Applications
• Efficient routing
• Efficient broadcasting
• Area monitoring
• Service discovery
• Minimum CDS is NP-complete

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Research Efforts

• Many works seek a minimum connected dominating
  set (MCDS) in unit-disk graphs as their major
  design goal
• Performance bounds is their primary design
  parameter

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MCDS for CDS (Das et al, UIUC, 1997)

• Select a node with global maximal degree as root
• Grow a tree by adding nodes with maximal
  effective degrees
• Centralized
• size at most 2(1 H(d)) OPT
• d is the maximum degree of the input graph and H
  is the harmonic function

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Clustering Method for CDS (LinGerla, UCLA, 1996)

• Min-ID
• Select nodes with minimal IDs in 1 hop neighbors
  as cluster heads
• Select gateways to connect cluster heads
• localized

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Pruning Based CDS Construction (Wu and Lis)

• Marking process
• Initially all vertices are unmarked
• any vertex having two unconnected neighbors is
  marked as a dominator
• Pruning
• Rule 1u can withdrew if there exists a neighbor
  v with higher ID be a neighbor to all neighbors
  of u
• Rule 21u can withdrew if there exist two
  connected neighbors v and w with higher IDs be
  neighbors to all neighbors of u
• Rule k

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Research Scope
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I. Extended CDS in CC Model
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Cooperative Communication Model

• Cooperative communication (CC)
• physical layer design
• combine several partial signals to achieve the
  original signal
• Combine the advantages
• power savings
• spatial diversity
• increased data rates

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Extended CDS (ECDS) in CC Model

• A node set is an EDS if every node is
• in the set,
• a regular neighbor of a node in the set, or
• a quasi neighbor of k nodes in the set
• Connectivity in CC model
• Strongly connectivity ECDS
• Weakly connectivity EWCDS
• EDS, ECDS, and EWCDS problems are NP-complete

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(a) A sample network with CDS u, v, w and
ECDS u, v. (b) Another sample with EWCDS x,
u, v. (k2)
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Solutions for ECDS Problems

• E-MCDS for EWCDS
• E-Clustering for EDS/ECDS
• E-AWF for EWCDS
• E-Rule K for ECDS

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MCDS for CDS (Das et al, UIUC, 1997)

• Select a node with global maximal degree as root
• Grow a tree by adding nodes with maximal
  effective degrees

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Extended MCDS for EWCDS

• Basic idea
• each node contributes 1 to all its neighbors and
  1/k to all quasi neighbors if selected
• Global solution
• Select a node with maximal contribution as the
  root
• Grow a tree by adding nodes with maximal
  effective contribution

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20 nodes, 4 selected, k2
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Questions/Comments

• http//cs.rpi.edu/yangs6