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

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 Proto

col (BTCP)Consist of three Phases

Coordinator electionRole determinationActual 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 coordinatorBluetree

A rooted spanning tree

Introduction(3/4)

Z. Wang et al. , “Bluenet – a New Scatternet Formation Scheme”Distributed protocol that does not requir any

coordinatorBetter performance when compared with Bl

uetree

Introduction(4/4)

Phase 1： Control Scatternet FormationControl Scatternet is constructed which is u

sed for control and signaling purposesPhase 2： On-Demand Scatternet Form

ationCreate an On-demand Scatternet whenever

a node wants to exchange data with other nodes

Phase 1： Control Scatternet Formation

Scatternet Formation AlgorithmScheduling in the Control ScatternetSupport of Topology Changes

Scatternet Formation Algorithm

Minimize the number of piconetsPutting the slave nodes into park mode

Support dynamic topology changes

M M

Scatternet Formation Algorithm

Period 1 Sensing Neighbors

Period 2 Election of Master Nodes

Period 3 Connection of Piconets into Scatternet

0 T0 T1

Period 1 Period 2 Period 3

Period 1 Sensing Neighbors

Inquiry Inquiry Scan

Inquiry

Inquiry Scan

NIB： Neighbor Information Base

Period 1 Sensing Neighbors

Inquiry Inquiry ScanEID Packet

Period 1 Sensing Neighbors

3M M

M

3 4

2

13

4

Period 2 Election of Master Nodes

Rule R0: Node i keeps Ri = UNDEFINED if there exists a node j∈Fi such t

hat 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 tha

t Rj =MASTER; or. Ri = BRIDGEn if there exists n nodes j ∈ Fi such th

at 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, an

d 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.

2

2

3

2

12M

Period 2 Election of Master Nodes

Rule R2: Node i sets Ri = MASTER if, for all j∈Fi , Rj =UNDEFINED, an

d 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.

3

2

3

2 2

3

2

78

Period 2 Election of Master Nodes

Rule R2: Node i sets Ri = MASTER if, for all j∈Fi , Rj =UNDEFINED, an

d 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.

3

2

3

2

3

2

7 7

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 MB

Period 3 Connection of Piconets into Scatternet

MasterPage

Other NodesPage Scan M M

B3

B2

MB21. Slaves

2. Bridges① Highest degree② 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 nodesMaster：

Accept new nodeCommunication

Support of Topology Changes

MB2

M

C

D

Device D：BD addrClock

Support of Topology Changes

MB2

M

C

D

Period 2 ：Rule 0

Page Scan

Support of Topology Changes

Master leavesChoose 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 SelectionPath Request (PREQ)Path Reply (PREP)

s

M

B

p

m

d

s M m d

s p dPREQ

d p

Page Page Scan

d’s BD addrclock

pPage s

d p s

M/S relay

Performance Analysis

BTCP 36 nodes 8 piconets Theoretical maximum throughput

723.2 kbps * 8 = 5.7856 Mbps

TPSF 36 nodes 1 piconets Theoretical maximum throughput

723.2 kbps * 17 = 12.2944 Mbps

Performance Analysis

Simulation time is 105 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 efficiencySupporting dynamic changes in network top

ology