1. Department of Information Engineering University of Padova, ITALY A Soft QoS scheduling algorithm for Bluetooth piconets {andrea.zanella, daniele.miorandi, silvano.pupolin, freccia}@dei.unipd.it Andrea Zanella, Daniele Miorandi, Silvano Pupolin, Cristian Andreola WPMC 2003, 21-22 October 2003 Special Interest Group on NEtworking & Telecommunications

2. WPMC 2003, Yokosuka, 21-22 October, 2003 TD (03)-097 Outline of the contents  Motivations & Purposes  Bluetooth Basic  Hard-QoS & Soft-QoS  Soft-QoS for Bluetooth: SFPQ  Results and Demostration  Concluding Remarks

3. WPMC 2003, Yokosuka, 21-22 October, 2003 TD (03)-097 What and Why… Motivations & Purposes

4. WPMC 2003, Yokosuka, 21-22 October, 2003 TD (03)-097 Motivations  Demand for QoS support over portable electronic devices is increasing:  audio/video streaming  interactive games  multimedia  Unfortunately, Bluetooth does not provide native QoS support…

5. WPMC 2003, Yokosuka, 21-22 October, 2003 TD (03)-097 Aim of the study  Adding Soft-QoS support to BT piconets  Definition of Soft-QoS parameters  Design of Soft-QoS scheduling algorithm  Analisys of the proposed algorithm

6. WPMC 2003, Yokosuka, 21-22 October, 2003 TD (03)-097 What the standard says… Bluetooth basic

7. WPMC 2003, Yokosuka, 21-22 October, 2003 TD (03)-097 Bluetooth piconet piconet  Two up to eight Bluetooth units sharing the same channel form a piconet  In each piconet, a unit acts as master, the others act as slaves centralized polling scheme  Channel access is based on a centralized polling scheme Time-division- duplex  Full-duplex is supported by Time-division- duplex (TDD), with time slots of T=0.625 ms active slave master parked slave standby slave1 slave2 slave3 master

8. WPMC 2003, Yokosuka, 21-22 October, 2003 TD (03)-097 Multi-slot packets  Data packets can be:  1, 3, or 5 slot long  Unprotected or 2/3 FEC protected  Unprotected packet formats (DH)  higher data capacity  more subject to errors  Protected packet formats (DM):  medium data capacity  higher protection against errors

9. WPMC 2003, Yokosuka, 21-22 October, 2003 TD (03)-097 Introduction to QoS issues QoS in Bluetooth networks

10. WPMC 2003, Yokosuka, 21-22 October, 2003 TD (03)-097 Resource Allocation  Different types of applications:  Web Browsing Medium-to-high data rate  Streaming audio Low delay and jitter High data rate  Voice Low delay and jitter Low data rate

11. WPMC 2003, Yokosuka, 21-22 October, 2003 TD (03)-097 Hard & Soft QoS  Hard QoS  Widely used in wired networks Integrated Services: flow based (RSVP) Differentiated Services: class based  Soft QoS  Suitable for wireless networks Applications may work even if, for short periods of time, QoS requirements are not satisfied Deal with limited bandwith and radio channel

12. WPMC 2003, Yokosuka, 21-22 October, 2003 TD (03)-097 FPQ algorithm  Aim: providing Hard QoS support by means of a Fair and efficient Polling scheme*  QoS parameters required for each link  Expected data rate  Maximum acceptable delay  Adjust priorities of the slaves on the basis of  Slaves’ queue length estimation  Traffic parameters  QoS parameters *[FPQ: a fair and efficient polling algorithm with QoS support for Bluetooth piconet, INFOCOM03]

13. WPMC 2003, Yokosuka, 21-22 October, 2003 TD (03)-097 FPQ scheme  Purpose  Determine the most efficient polling sequence fulfilling QoS requirements  Slave Analyzer determines  P data : probability of having queued packets  NSLP: interval of time since last POLL/NULL sequence  Selection Algorithm  Determine priority of each data flow  Select the master/slave link with highest priority  Limits  Inefficient service differentiation under high traffic loads

14. WPMC 2003, Yokosuka, 21-22 October, 2003 TD (03)-097 Soft QoS support Soft-FPQ algorithm for Bluetooth piconets

15. WPMC 2003, Yokosuka, 21-22 October, 2003 TD (03)-097 Soft-FPQ algorithm  Aim: Providing Soft QoS by means of dynamic estimation of flows’ satisfaction  Definition of a new Soft QoS parameter: Target Satisfaction  Priorities are adjusted according to QoS parameters and the estimated satisfaction margin for each slave Low traffic: high satisfaction for all flows High traffic: distribute resources to fulfill exactly QoS request

16. WPMC 2003, Yokosuka, 21-22 October, 2003 TD (03)-097 Soft QoS parameters  Average packet inter-arrival time: ITL  Average packet length: PL  Maximum sustainable packet delay: MD  Target Satisfaction index  Percentage of packets that are expected to satisfy the QoS constrains

17. WPMC 2003, Yokosuka, 21-22 October, 2003 TD (03)-097 Dynamic Satisfaction estimation Estimated Satisfaction: Arrival time: Probability: Arrival rate: Empty queue

18. WPMC 2003, Yokosuka, 21-22 October, 2003 TD (03)-097 Example of dynamic estimation

19. WPMC 2003, Yokosuka, 21-22 October, 2003 TD (03)-097 Istantaneous Satisfaction  Estimated Satisfaction is updated anytime an AP packet is received  To cope with long silence periods of slaves, we introduce the Istantaneous Satisfaction that is updated slot by slot according to function  …  Istantaneous satisfaction is reset at the first AP arrival Maximum Delay Number of points

20. WPMC 2003, Yokosuka, 21-22 October, 2003 TD (03)-097 Satisfaction Margins Satisfaction Margin: Normalized Satisfaction Margin: Actual Satisfaction Target Satisfaction

21. WPMC 2003, Yokosuka, 21-22 October, 2003 TD (03)-097 Priority Evaluation Constants:  Traffic Demand  QoS Request Fairness Normalized Satisfaction Index

22. WPMC 2003, Yokosuka, 21-22 October, 2003 TD (03)-097 NS2 Simulation Simulation of QoS Bluetooth Piconet

23. WPMC 2003, Yokosuka, 21-22 October, 2003 TD (03)-097 Simulation Scenario  Piconet with 7 slaves  Only upstream traffic  One application per slave  One application  =1 (Hard QoS)  One application  =0.9  One streaming video application  =0.9  4 Best Effort applications  =0.2  Simulation dynamic  Slaves with high  are active for all the simulation time  Best Effort transmissions start sequentially seconds apart  When all the applications are active the system gets congested

24. WPMC 2003, Yokosuka, 21-22 October, 2003 TD (03)-097 Satisfaction perceived (1/3) Target Satisfaction:  =1 Heavy Load

25. WPMC 2003, Yokosuka, 21-22 October, 2003 TD (03)-097 Satisfaction perceived (2/3) Target Satisfaction:  =0.9 Heavy Load

26. WPMC 2003, Yokosuka, 21-22 October, 2003 TD (03)-097 Satisfaction perceived (3/3) Target Satisfaction:  =0.2

27. WPMC 2003, Yokosuka, 21-22 October, 2003 TD (03)-097 Delay Distribution  Video Streaming Delay Distribution  Low traffic  Video Streaming Delay Distribution  High traffic

28. WPMC 2003, Yokosuka, 21-22 October, 2003 TD (03)-097 Video Streaming Demo  Scenario  Upstream traffic only  One application per slave  One application streaming video,  =0.9  Two Best Effort application,  =0.2  Demo Structure  RTP Server: send packets of video stream  RTP Client: receive packets and display video  Delay: introduce pre- computed packet delays FPQ SFPQ

29. WPMC 2003, Yokosuka, 21-22 October, 2003 TD (03)-097 Conclusions & Future work  Support of Soft QoS in Bluetooth  Better service differentiation  Efficient resource distribution  Better support to real time and audio/video streaming applications  Better behavior of the piconet under high traffic conditions  Next steps  Improve algorithms setting and introduce dynamic parameters tuning  Extension of the algorithm to Scatternet structures  Development of low complexity Satisfaction Estimation algorithms

30. WPMC 2003, Yokosuka, 21-22 October, 2003 TD (03)-097 That’s all! Thanks for your attention!