University of Padova Department of Information Engineering On

University of Padova Department of Information Engineering On the Optimal Topology of Bluetooth Piconets: Roles Swapping Algorithms A note on the use of these ppt slides: We’re making these slides freely available to all, hoping they might be of use for researchers and/or students. They’re in Power. Point form so you can add, modify, and delete slides (including this one) and slide co ntent to suit your needs. In return for use, we only ask the following: If you use these slides (e. g. , in a class, presentations, talks and so on) in substantially unaltered form, that you mention their source. If you post any slides in substantially unaltered form on a www site, that you note that they are adapted from (or perhaps identical to) our slides, and put a link to the authors webpage: www. dei. unipd. it/~zanella Thanks and enjoy!

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

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

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

System Model Cluster of N+1 nodes (N 7) Assumptions All nodes are in-range Independent Poisson traffic model Definitions Δ={δi, j}: End-to-end traffic matrix Λ={λi, j}: Effective traffic pattern matrix k: master unit P={k, Δ}: piconet D. Miorandi & A. Zanella Med-Hoc-Net, Chia, 6 September 2002

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 following conditions hold: is fully admissible if and only if the Proposition: A traffic matrix following conditions hold: is admissible if and only if the D. Miorandi & A. Zanella Med-Hoc-Net, Chia, 6 September 2002

Optimal Criterion Average link delay: Average packet delay Total offered traffic Average network delay Criterion I: choose k s. t. D. Miorandi & A. Zanella Med-Hoc-Net, Chia, 6 September 2002

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

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. [N=5, matrix entries uniformly distributed in (0, 1)] D. Miorandi & A. Zanella Med-Hoc-Net, Chia, 6 September 2002

Results (2) The delays are significantly higher in the sparse case. Both criterion offer valuable performance improvement. [N=5, matrix entries uniformly distributed in (0, 1), average density of 0. 4] D. Miorandi & A. Zanella Med-Hoc-Net, Chia, 6 September 2002

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

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

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