A Two-Phase Scatternet Formation Protocol for Bluetooth Wireless Personal Area Networks

1. A Two-Phase Scatternet Formation Protocol forBluetooth Wireless Personal Area Networks Yoji Kawamoto, Vincent W.S. Wong, and Victor C.M. Leung Bluetooth and Wireless Personal Area Networks ,WCNC 2003 Speaker：Chi-Chih Wu

2. Outline • Introduction • Phase 1：Control Scatternet Formation • Scatternet Formation Algorithm • Scheduling in the Control Scatternet • Support of Topology Changes • Phase 2：On-Demand Scatternet Formation • Performance Analysis • Conclusions

3. Introduction(1/4) • T. Salonidis et al. , “Distributed Topology Construction of Bluetooth Personal Area Networks” • The Bluetooth Topology Construction Protocol (BTCP) • Consist of three Phases • Coordinator election • Role determination • Actual connection establishment

4. Introduction(2/4) • G. V. Zaruba et al. , “Bluetrees – Scatternet Formation to Enable Bluetooth-Based Ad Hoc Networks” • Blueroot • A piconet is first Constructed by a coordinator • Bluetree • A rooted spanning tree

5. Introduction(3/4) • Z. Wang et al. , “Bluenet – a New Scatternet Formation Scheme” • Distributed protocol that does not requir any coordinator • Better performance when compared with Bluetree

6. Introduction(4/4) • Phase 1：Control Scatternet Formation • Control Scatternet is constructed which is used for control and signaling purposes • Phase 2：On-Demand Scatternet Formation • Create an On-demand Scatternet whenever a node wants to exchange data with other nodes

7. Phase 1：Control Scatternet Formation • Scatternet Formation Algorithm • Scheduling in the Control Scatternet • Support of Topology Changes

8. Scatternet Formation Algorithm • Minimize the number of piconets • Putting the slave nodes into park mode • Support dynamic topology changes M M

9. Scatternet Formation Algorithm • Period 1 • Sensing Neighbors • Period 2 • Election of Master Nodes • Period 3 • Connection of Piconets into Scatternet Period 2 Period 3 Period 1 T0 T1 0

10. Inquiry Inquiry Scan Inquiry Scan Inquiry Period 1 Sensing Neighbors NIB：Neighbor Information Base

11. Period 1 Sensing Neighbors Inquiry Inquiry Scan EID Packet

12. M M 4 3 3 13 M 4 2 Period 1 Sensing Neighbors

13. M R M Period 2 Election of Master Nodes • Rule R0: Node i keeps • Ri = UNDEFINEDif there exists a node j∈Fi such that Dj = CONNECTED. Otherwise, go to rule R1.

14. Slave M BRIDGE2 M Period 2 Election of Master Nodes • Rule R1: Node i sets. • Ri = SLAVEif there exists one node j ∈ Fi such that Rj =MASTER; or. • Ri = BRIDGEnif there exists nnodes j ∈ Fi such that Rj =MASTER;. • Otherwise, go to rule R2.

15. 2 2 1 2 3 2 Period 2 Election of Master Nodes • Rule R2: Node i sets • Ri = MASTERif, for all j∈Fi , Rj =UNDEFINED, and one of the conditions is true: • (a) Gi > Gj, • (b) Vi < Vk for all k ∈ Fi and Gi = Gk , • (c) Ui < Uk for all k ∈ Fi and Gi = Gk and Vi = Vk. M

16. 2 2 8 3 7 3 3 2 2 Period 2 Election of Master Nodes • Rule R2: Node i sets • Ri = MASTERif, for all j∈Fi , Rj =UNDEFINED, and one of the conditions is true: • (a) Gi > Gj , • (b) Vi < Vk for all k ∈ Fi and Gi = Gk , • (c) Ui < Uk for all k ∈ Fi and Gi = Gk and Vi = Vk.

17. 2 7 3 7 3 3 2 BD Addr 2 Period 2 Election of Master Nodes • Rule R2: Node i sets • Ri = MASTERif, for all j∈Fi , Rj =UNDEFINED, and one of the conditions is true: • (a) Gi > Gj , • (b) Vi < Vk for all k ∈ Fi and Gi = Gk , • (c) Ui < Uk for all k ∈ Fi and Gi = Gk and Vi = Vk.

18. Period 2 Election of Master Nodes • Rule R3: If Ri = MASTER, then set • Ri = SLAVEif there exists node j ∈ Fi such that Rj = MASTERand Uj < Ui. • Not Starting their algorithms at the same time • Loss of neighbor information due to transmission errors M M BD Addr

19. M M B Period 2 Election of Master Nodes • Rule R4: If Ri ≠ MASTERand Rj ≠ MASTERfor all nodes j ∈ Fi over some time in period 2, then repeat master election procedure using rule R2 for role determination. • If the new node fails to connected to a master after the expiration T1

20. Period 3 Connection of Piconets into Scatternet • Master • Page • Other Nodes • Page Scan Broadcast neighbor information received form adjacent piconets to all node M M B3 B2 B2 • Slaves • Bridges • Highest degree • Smallest BD Addr M Master send all of its slave and bridge node’s information

21. Scheduling in the Control Scatternet • Time Slot Scheduling Mechanism • Pure slaves period • Bridge node period • Sleep period

22. M M B2 Scheduling in the Control Scatternet • Time Slot Scheduling Mechanism • Sense for adjacent nodes • Master： • Accept new node • Communication

23. Support of Topology Changes D M B2 M Device D： BD addr Clock C

24. Support of Topology Changes Period 2 ： Rule 0 D M Page Scan B2 M C

25. Support of Topology Changes • Master leaves • Choose a new master node in its NIB • Bridge leaves • Inform its master, which will choose another bridge node those in their NIBs

26. RREQ s d RREQ M, m M m B RREP Phase 2：On-Demand Scatternet Formation • Step 1：Route Selection based on DSR • Route Request Packet (RREQ) • Route Reply Packet (RREP)

27. s M m d s p d Page Page Scan d p d’s BD addr clock Phase 2：On-Demand Scatternet Formation Step 2：Participating Nodes Selection • Path Request (PREQ) • Path Reply (PREP) s PREQ d p M m Page p s B d p s M/S relay

28. Performance Analysis • BTCP • 36 nodes • 8 piconets • Theoretical maximum throughput723.2 kbps * 8 = 5.7856 Mbps • TPSF • 36 nodes • 1 piconets • Theoretical maximum throughput723.2 kbps * 17 = 12.2944 Mbps

29. Performance Analysis • Simulation time is 105 time slots • Each slot corresponds to 625 µs • Each point is average over 1000 simulation runs

30. Conclusions • Two-phase scatternet formation (TPSF) protocol • Improve the communication efficiency • Supporting dynamic changes in network topology