A Two-Phase Scatternet Formation Protocol for Bluetooth 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

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

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

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

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

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

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

Scatternet Formation Algorithm Minimize the number of piconets Putting the slave nodes into park mode Support dynamic topology changes MM

Scatternet Formation Algorithm Period 1 Sensing Neighbors Period 2 Election of Master Nodes Period 3 Connection of Piconets into Scatternet 0 T0T1 Period 1 Period 2Period 3

Period 1 Sensing Neighbors InquiryInquiry Scan Inquiry Inquiry Scan NIB ： Neighbor Information Base

Period 1 Sensing Neighbors InquiryInquiry Scan EID Packet

Period 1 Sensing Neighbors 3 MM M

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

Period 2 Election of Master Nodes Rule R1: Node i sets. Ri = SLAVE if there exists one node j ∈ Fi such that Rj =MASTER; or. Ri = BRIDGEn if there exists n nodes j ∈ Fi such that Rj =MASTER;. Otherwise, go to rule R2. M M Slave BRIDGE2

Period 2 Election of Master Nodes Rule R2: Node i sets Ri = MASTER if, 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

Period 2 Election of Master Nodes Rule R2: Node i sets Ri = MASTER if, 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

Period 2 Election of Master Nodes Rule R2: Node i sets Ri = MASTER if, 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 BD Addr

Period 2 Election of Master Nodes Rule R3: If Ri = MASTER, then set Ri = SLAVE if there exists node j ∈ Fi such that Rj = MASTER and Uj < Ui. M M BD Addr 1.Not Starting their algorithms at the same time 2.Loss of neighbor information due to transmission errors

Period 2 Election of Master Nodes Rule R4: If Ri ≠ MASTER and Rj ≠ MASTER for 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 M M B

Period 3 Connection of Piconets into Scatternet Master Page Other Nodes Page Scan M M B3 B2 M 1.Slaves 2.Bridges Highest degree ‚Smallest BD Addr Master send all of its slave and bridge node’s information Broadcast neighbor information received form adjacent piconets to all node

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

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

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

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

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

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

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

Performance Analysis BTCP 36 nodes 8 piconets Theoretical maximum throughput kbps * 8 = Mbps TPSF 36 nodes 1 piconets Theoretical maximum throughput kbps * 17 = Mbps

Performance Analysis Simulation time is 10 5 time slots Each slot corresponds to 625 µs Each point is average over 1000 simulation runs

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