1. Sep. 18, 2003Chung-Hsien Hsu A Dynamic Slot Assignment Scheme for Slave-to-Slave and Multicast-like Communication in Bluetooth Personal Area Networks C. M. Cordeiro, S. Abhyankar, and D. P. Agrawal OBR Center for Distributed and Mobile Computing Department of ECECS, University of Cincinnati To Appear in IEEE Globecom 2003 and ACM/IFIP PWC 2003 Reporter: Chung-Hsien Hsu

2. Sep. 18, 2003Chung-Hsien Hsu Outline Introduction The Dynamic Slot Assignment (DSA) Scheme Connection Request Connection Release Slot Scheduling and Assignment Example Scenario Simulation Conclusion

3. Sep. 18, 2003Chung-Hsien Hsu Introduction – Bluetooth Overview Two link types: Synchronous Connection Oriented (SCO) Circuit-switched. To use for audio applications. Strict QoS requirement. Packet type: HV1,2,3 Asynchronous Connectionless Link (ACL) Packet-switched. To use in data applications. No such strict requirement on end-to-end delay. Packet type: DH 1, 3,5 and DM 1, 3,5

4. Sep. 18, 2003Chung-Hsien Hsu Introduction – Motivation The Master/Slave paradigm of Bluetooth should not be adopted in its current form Bandwidth is wasted by forwarding through the master. End-to-end packet delay increases. Power consumption is significantly increased at the master unit. Communication with one deviceCommunication with more than one device

5. Sep. 18, 2003Chung-Hsien Hsu Dynamic Slot Assignment (DSA) Basic idea: To appropriately manage the polling cycle conducted by the master of the piconet. As devices initiate or terminate communication with each other Master restructure the piconet polling cycle Propagating the resulting schedule to the members of the piconetSlaves communicate directly

6. Sep. 18, 2003Chung-Hsien Hsu Dynamic Slot Assignment (DSA) – Connection Request CONNECTION_REQ Destination(s) Baseband packet type Desired transmission rate Acceptable transmission rate M S1 S2S3 S4 CONNECTION_REQ(S3, DH5, 30, 50) CONNECTION_REJ SLOT_SCHED Connection ID = C 1,3

7. Sep. 18, 2003Chung-Hsien Hsu Dynamic Slot Assignment (DSA) – Connection Release CONNECTION_REL Connection identifier M S1 S2S3 S4 Connection ID = C 1,3 CONNECTION_REL(C 1,3 ) SLOT_SCHED

8. Sep. 18, 2003Chung-Hsien Hsu Dynamic Slot Assignment (DSA) – Slot Scheduling and Assignment Master computes a new schedule for devices when it receives either a connection request or termination. Which slot(s) belong to which device. In which slot(s) a given slave needs to listen. Using broadcast method to inform all devices. Broadcasting the same message three tiemes.

9. Sep. 18, 2003Chung-Hsien Hsu Dynamic Slot Assignment (DSA) – Slot Scheduling and Assignment (cont.) Providing both unicast and multicast-like communication within a piconet by using this single message format. SCO connections are treated differently Which have a fixed scheduling. SLOT_SCHED HeaderNew Connection Info.New and Existing ACL Connections Info.

10. Sep. 18, 2003Chung-Hsien Hsu Dynamic Slot Assignment (DSA) – Slot Scheduling Message Format HeaderNew Connection Info.New and Existing ACL Connections Info. # ACL Conn.# DestinationsSCO/ACL 134 …New Conn. Number# Slots AssignedDest. i Add.Source Add. 3 3*(# Destinations) 24 TxSlotSlot-Cycle…Conn. # i 4*(# ACLConn.) 88 Slot-Cycle is always a multiple of 6. Assumption CONN thres = 16

11. Sep. 18, 2003Chung-Hsien Hsu Dynamic Slot Assignment (DSA) – Example Scenario M S1 S2S3 S4 CONNECTION_REQ(S2, DH5, 30, 50) Slot-Cycle = 6 Polling

12. Sep. 18, 2003Chung-Hsien Hsu Dynamic Slot Assignment (DSA) – Example Scenario M S1 S2S3 S4 C 1,2 Polling ( priority is given to those devices currently without open connections. ) 111125C 1,2 112 CONNECTION_REQ(S2, DH5, 30, 50) SLOT_SCHED Slot-Cycle = 6

13. Sep. 18, 2003Chung-Hsien Hsu Dynamic Slot Assignment (DSA) – Example Scenario M S1 S2S3 S4 CONNECTION_REQ(S4, DH3, 20, 40) C 1,2 Slot-Cycle = 12 Polling

14. Sep. 18, 2003Chung-Hsien Hsu Dynamic Slot Assignment (DSA) – Example Scenario M S1 S2S3 S4 112343C 3,4 C 1,2, C 3,4 118 CONNECTION_REQ(S4, DH3, 20, 40) SLOT_SCHED C 1,2 Slot-Cycle = 18 Polling C 3,4 Slots = ( polling_cycle * index_in_list ) + TxSlot

15. Sep. 18, 2003Chung-Hsien Hsu Simulation Environment Simulator: BlueHoc Device: 8 (using a single piconet) Region: 7m x 7m Radio range: 10m Channel capacity: 1Mbps Compare with the existing Bluetooth

16. Sep. 18, 2003Chung-Hsien Hsu Simulation (cont.) Comparing metrics: Aggregate Throughput Delay Overhead Power Consumption Traffic scenarios: Scenario A: 3 FTP connections are initiated consecutively in different points in time. Scenario B: 2 SCO connections are initiated consecutively in different points in time. Scenario C: 3 connections (SCO, Telnet, FTP) are initiated consecutively.

17. Sep. 18, 2003Chung-Hsien Hsu Simulation (cont.) – Aggregate Throughput

18. Sep. 18, 2003Chung-Hsien Hsu Simulation (cont.) – Aggregate Throughput

19. Sep. 18, 2003Chung-Hsien Hsu Simulation (cont.) – Delay

20. Sep. 18, 2003Chung-Hsien Hsu Simulation (cont.) – Delay

21. Sep. 18, 2003Chung-Hsien Hsu Simulation (cont.) – Overhead

22. Sep. 18, 2003Chung-Hsien Hsu Simulation (cont.) – Overhead

23. Sep. 18, 2003Chung-Hsien Hsu Simulation (cont.) – Power Consumption

24. Sep. 18, 2003Chung-Hsien Hsu Simulation (cont.) – Power Consumption

25. Sep. 18, 2003Chung-Hsien Hsu Conclusions Proposing a dynamic scheduling scheme Implementation of direct communication between any two slaves within a piconet. Support for multicast-like transmissions for group communication. DSA outperform existing Bluetooth Providing optimal bandwidth usage Lower delay Low overhead

26. Sep. 18, 2003Chung-Hsien Hsu Compare with Time-Slot leasing approach Similarity: Master allocate slots to slave for direct communication. Differences: SCO connection. Provide for multicast-like communication. Dynamically adjusts the slot cycle so as to meet traffic needs.

27. Sep. 18, 2003Chung-Hsien Hsu Dynamic Slot Assignment (DSA) – Slot Scheduling Message Format HeaderNew Connection Info.New and Existing ACL Connections Info. # ACL Conn.# DestinationsSCO/ACL 134 …New Conn. Number# Slots AssignedDest. i Add.Source Add. 3 3*(# Destinations) 24 TxSlotSlot-Cycle…Conn. # i 4*(# ACLConn.) 88