1. A Bluetooth Scatternet-Route Structure for Multihop Ad Hoc Networks Yong Liu, Myung J. Lee, and Tarek N. Saadawi 2003 IEEE Journal on Selected Areas in Communications speaker ： ChiChih Wu

2. Outline Introduction Overview of Bluetooth Technology Scatternet-Route Structure and It’s on-Demand Formation Structure Design On-Demand Formation of Scatternet Route Scatternet Scheduling Performance of Scatternet-Route Simulation Results Conclusion

3. Introduction [1] Xu and Saadawi, “Does the IEEE 802.11 MAC protocol work well in multihop wireless ad hoc networks?” The existence of sensing range is typically larger than the usually considered transmission range IEEE 802.11 cannot solve the hidden terminal and exposed terminal problems in multihop wireless networks These problems may eventually lead to serious TCP instability and unfairness

4. Introduction [2] Specification of the Bluetooth System [Online] Different piconets employ frequency hopping code- division multiple-access (FH-CDMA) channels to prevent mutual interferences Bluetooth specification defines a scatternet structure( within a scatternet, two Bluetooth device with their distance larger than their transmission range, but less than their sensing range use different time slot or stay in different piconet without interfering each other ) Hidden terminal 、 Exposed terminal can be eliminated

5. Introduction [8] B. Raman et al., “Arguments for cross-layer optimizations in Bluetooth scatternets” [9] P. Johansson et al., “Bluetooth:An enabler for personal area networking” The unnecessary link maintenance wastes plenty of power Suggest the integration of scatternet link formation with on-demand routing

6. Overview of Bluetooth Technology Frequency Hopping Code-Division Multiple-Access (FH-CDMA) 625 µs Point-to-Point link establish Inquiry Inquiry Scan Page Page Scan

7. Overview of Bluetooth Technology Inquiry ： 32 frequencies of the inquiry hopping sequences are divided into two 16-hop parts, named A train and B train A single train must be repeated 256 times Each train period least 2.56 s At least three train switches (10.24 s) Inquiry Scan ： random backoff Page Scan Interval ： 1.28s ( mode R1)

8. Scatternet-Route Structure and It’s On-Demand Formation The Differences between “Scatternet-Route Structure” and “Big Scatternet Structure” Traffic Dependency Network Coverage Combination with Routing Scatternet Information ： Data Link Layer Scatternet Routing S D master relay slave

9. Scatternet-Route Structure and It’s on-Demand Formation Structure Design Possible Structure of The Scatternet Route Single Role Approach Double Role Approach Higher Throughput Lower Delay Robust to The Network Variations

10. Scatternet-Route Structure and It’s on-Demand Formation Structure Design Serve in four piconets Serve in three piconets

11. Scatternet-Route Structure and It’s On-Demand Formation Structure Design Time frame

12. Scatternet-Route Structure and It’s on-Demand Formation On-Demand Formation of Scatternet Route Like most of the on-demand routing protocols Flooding Route-discovery-packet (RDP) Route-reply-packet (RRP) Flooding-Based Route Discovery L2CAP Broadcast LMP Broadcast EID Broadcast

13. Scatternet-Route Structure and It’s on-Demand Formation On-Demand Formation of Scatternet Route L2CAP Broadcast RDP broadcast in the L2CAP layer Inquiry Page 6 * ( 10.24 + 0.64 * 3 ) + ( 10.24 + 0.64 ) = 83.84s

14. Scatternet-Route Structure and It’s on-Demand Formation On-Demand Formation of Scatternet Route LMP Broadcast Inquiry Page 7 * ( 10.24 + 0.64 ) = 76.16s 1.25ms

15. Scatternet-Route Structure and It’s on-Demand Formation On-Demand Formation of Scatternet Route EID (Extended ID) Broadcast The inquiry and page processes Synthesizer

16. Scatternet-Route Structure and It’s on-Demand Formation On-Demand Formation of Scatternet Route EID Broadcast Source 、 Destination 、 Upstream BD_ADDR Upstream clock ， Packet sequence number ， EID type…etc. At least 182 bits ： EID packet (Type 1 、 Type 2) ISIs(Inquiry scan intervals 5.12s 17.92s 2.56s 8.96s 0.64s 2.24s

17. Scatternet-Route Structure and It’s on-Demand Formation On-Demand Formation of Scatternet Route Scatternet Formation Route Setting Route-Wide Synchronization RRP

18. Scatternet-Route Structure and It’s on-Demand Formation Scatternet Scheduling Initial Visit Period ( IVP ) Visit Neighbors Periodically

19. Performance of Scatternet-Route Scatternet-Route Throughput n x l ( 2 x n x m + s yn ) x t f n ： One relay device each time collect n packet l ： Packet with the size of l m ： l costs m time frames s yn ： Synchronized factor t f ： each time frame has the length t f

20. Performance of Scatternet-Route Packet number Device ID

21. Simulation Results Destination is set as 3, 6, 9, …, 21

22. Simulation Results

25. Conclusions EID scheme can achieve an acceptable route setup delay in multihop ad hoc environment The scatternet-route structure can achieve high network utilization and stable route throughput