Presentazione di PowerPoint

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University of Padova

Department of Information Engineering
On the Optimal Topology of Bluetooth Piconets
Roles Swapping Algorithms

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University of Padova

Department of Information Engineering
On the Optimal Topology of Bluetooth Piconets
Roles Swapping Algorithms
Med-Hoc-Net 2002 , Chia (Italy), 6 September 2002
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Overview

• Intro to Bluetooth system
• Mathematical model
• Stability issues delay analysis
• Optimal criterion for off-line topologies design
• Suboptimal criterion for real-time network
  reconfiguration
• Conclusion discussion

Med-Hoc-Net, Chia, 6 September 2002
D. Miorandi A. Zanella
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Background BT system architecture

• Two up to eight active Bluetooth devices sharing
  the same FH channel form a piconet.
• In each piconet, a unit acts as a master, the
  others act as slaves.
• Channel access is based on a centralized polling
  scheme.
• Full duplex is achieved by means of time division
  duplexing (TDD).

Med-Hoc-Net, Chia, 6 September 2002
D. Miorandi A. Zanella
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System Model

• Cluster of N1 nodes (N?7)?
• Assumptions
• All nodes are in-range
• Independent Poisson traffic model
• Definitions
• ?di,j End-to-end traffic matrix
• ??i,j Effective traffic pattern matrix
• k master unit
• Pk, ? piconet

Med-Hoc-Net, Chia, 6 September 2002
D. Miorandi A. Zanella
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System Model (2)?

• Stability condition for the PRR polling scheme
• Definition A traffic matrix is admissible
  if there is a master choice k s.t. the stability
  condition holds (i.e. there is a stable
  topology).
• Definition A traffic matrix is fully
  admissible if the stability conditions hold for
  any choice of the master k.
• Proposition A traffic matrix is fully
  admissible if and only if the following
  conditions hold
• Proposition A traffic matrix is admissible
  if and only if the following conditions hold

Med-Hoc-Net, Chia, 6 September 2002
D. Miorandi A. Zanella
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Optimal Criterion

• Average link delay
• Average packet delay
• Total offered traffic
• Average network delay
• Criterion I choose k s.t.

Med-Hoc-Net, Chia, 6 September 2002
D. Miorandi A. Zanella
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Suboptimal Criterion

• Effective offered traffic
• Reasoning
• The more the effective traffic, the closer we get
  to the stability limit.
• The closer to the stability limit, the higher the
  delay.
• Criterion II choose k s.t.

Med-Hoc-Net, Chia, 6 September 2002
D. Miorandi A. Zanella
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Results (1)?

• At medium-to-high loads, both criterion offer a
  remarkable performance improvement.
• The suboptimal criterion leads to good results,
  even if far from optimality.

N5, matrix entries uniformly distributed in
(0,1)
Med-Hoc-Net, Chia, 6 September 2002
D. Miorandi A. Zanella
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Results (2)?

• The delays are significantly higher in the sparse
  case.
• Both criterion offer valuable performance
  improvement.

N5, matrix entries uniformly distributed in
(0,1), average density of 0.4
Med-Hoc-Net, Chia, 6 September 2002
D. Miorandi A. Zanella
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Applications

• Optimal design of a static Bluetooth piconet
  (e.g., sensor networks).
• Dynamic reconfiguration of a Bluetooth piconet
• The suboptimal criterion may be used to find
  efficient configurations (and adapt to varying
  traffic conditions).
• Connection admission control check for
  admissibility of the resulting traffic matrix.

Med-Hoc-Net, Chia, 6 September 2002
D. Miorandi A. Zanella
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Conclusion

• An analytical settlement for the characterization
  of efficient piconet topologies has been
  proposed.
• Two algorithms for the master choice (an optimal
  and a suboptimal with low computational
  complexity) have been presented.
• Simulation have been performed to show the impact
  on network performance.
• Some possible applications have been presented.
• Next step towards efficient scatternet
  topologies.

Med-Hoc-Net, Chia, 6 September 2002
D. Miorandi A. Zanella
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Any Questions?
?
Med-Hoc-Net, Chia, 6 September 2002
D. Miorandi A. Zanella