1. 10.03.2003presented by Hasan SÖZER 1 JUMP Mode A Dynamic Window-based Scheduling Framework for Bluetooth Scatternets Niklas Johansson Fredrik Alriksson Ulf Jönsson Switch Lab, Ericsson Research

2. 10.03.2003 presented by Hasan SÖZER2 Outline  Introduction  Rendezvous Window Distribution  Signaling of Presence  Scheduling Structure  Clock-drift & Power Saving Issues  Conclusion

3. 10.03.2003 presented by Hasan SÖZER3 Introduction... motivation  PMP: Participant in Multiple Piconets  PMP nodes have to switch in time-division bases; inter-piconet scheduling (IPS)  Effective scheduling is needed; Present when needed Identify absent PMPs  Availability & performance constraints should be considered

4. 10.03.2003 presented by Hasan SÖZER4 Introduction (2)... a tradeoff  Tradeoff concerning switching frequency Frequent: large switching overhead Infrequent: long delays

5. 10.03.2003 presented by Hasan SÖZER5 Introduction (3)... Sniff mode  SNIFF Mode (a power save mode) often proposed for scatternet operations periodic reocurring pause in communication conflict-free Has drawbacks; SNIFF parameters required throughout the scatternet Not flexible Changing topology would lead to renegotiation

6. 10.03.2003 presented by Hasan SÖZER6 Introduction (4)... Jump mode  JUMP Mode; an alternative mode Time is divided into time windows each of pseudo- random length; rendezvous windows (RV) Avoids systematic collusions & starvation Fully distributed Flexible Efficient Adaptible to different piconets and traffic conditions An alternative for power saving in Bluetooth

7. 10.03.2003 presented by Hasan SÖZER7 Introduction (5)... Jump mode  Jump mode link  PMP signals all concerned nodes when “jumping” to another piconet  PMP stands still during RV; Communicates with the members of the piconet based on intra-piconet scheduling mechanism  A framework is defined, not a specific inter- piconet scheduling algorithm

8. 10.03.2003 presented by Hasan SÖZER8 Rendezvous Window Distribution... usage  Jumping nodes schedule their activities using RVs of pseudo random length  Each node has its own unique sequence of RV fall into well-defined points; RV points  RV points are distributed in a random manner, based on some unique information of the node (So, others can calculate)  Randomness avoid systematic colliding  RV points are used for signaling

9. 10.03.2003 presented by Hasan SÖZER9 Rendezvous Window Distribution (2)... formation Time is divided into intervals of N sf frames In each interval one frame is pseudo randomly selected to become a RV point Time interval fall between two selected frames constitute a RV window

10. 10.03.2003 presented by Hasan SÖZER10 Rendezvous Window Distribution (3)... formation  Galois fields & FHSS algorithm are proposed for generation of unique pseudo-random RV windows  Bluetooth MAC address (BD_ADDR) can be fed into the random generator as the unique identifier of the node

11. 10.03.2003 presented by Hasan SÖZER11 Signaling of Presence... basics  Master Polls the jumping slave at its RV points. If it responds, Master assumes that the slave will be present until its next RV point and vice versa  Slave Selects the piconet to be present in the upcoming RV window, responds to the poll of the Master of the selected piconet in the corressponding RV point

12. 10.03.2003 presented by Hasan SÖZER12 Signaling of Presence (2)... basics  A Master PMP node does not necessarily have to set up JUMP mode towards its regular, non-PMP slaves

13. 10.03.2003 presented by Hasan SÖZER13 Signaling of Presence (3)... scenarios

14. 10.03.2003 presented by Hasan SÖZER14 Signaling of Presence (4)... scenarios LT2 acts as slave in all of its piconets At each RV point, LT2 responds to either Master LT2 is free to choose which piconet it wants to spend the next RV window in

15. 10.03.2003 presented by Hasan SÖZER15 Signaling of Presence (5)... scenarios LT1 acts as Master in Piconet 2 and as slave in Piconet 1 LT1 does not have to set up JUMP mode in Piconet 2 since none of the slaves is a PMP node and therefore should listen all the time

16. 10.03.2003 presented by Hasan SÖZER16 Signaling of Presence (6)... scenarios If LT1 fail to signal its presence at a RV point in Piconet 1, it could directly go back and serve Piconet 2 without having to wait until the next RV point

17. 10.03.2003 presented by Hasan SÖZER17 Signaling of Presence (7)... scenarios Network Access Point (NAP) illustrates a Master having several jumping slaves Intra-piconet scheduler is responsible for allocating the capacity among active units in the piconet

18. 10.03.2003 presented by Hasan SÖZER18 Signaling of Presence (8)... scenarios  If RV points of two jumping slaves collide, Master chooses one of them to poll  Pseudo-randomness avoids systematic collisions  Non-PMP slaves are not affected by the signaling protocol, they continuously listen  Non-PMP slaves do not receive poll messages when Master is a PMP node and it jumps to the other piconet

19. 10.03.2003 presented by Hasan SÖZER19 Signaling of Presence (9)... jumping slave signaling  Jumping slaves may set up a long-term schedule Advantages: Reduced overhead Less fragmented intra-piconet schedule Improved robustness Disadvantages Less flexible (traffic should be static)  Mixed long-term schedule can be used some RVs are fixed, some are processed with the basic signaling scheme

20. 10.03.2003 presented by Hasan SÖZER20 Signaling of Presence (10)... jumping Master signaling  Master can signal its presence and absence to its connected slaves. By this way; Peer node can act as jumping slave Slave can save power when Master is gone  Master can utilize its own RV points and broadcast its presence Broadcast message may not be received  A RV window can be reserved for each piconet through which Master’s schedule is transmitted

21. 10.03.2003 presented by Hasan SÖZER21 Signaling of Presence (11)... connected jumping nodes

22. 10.03.2003 presented by Hasan SÖZER22 Signaling of Presence (12)... connected jumping nodes  Jumping nodes may act as a Master towards the other jumping node  Jumping masters should not poll the jumping slaves when they are absent  Jumping slaves may arrange their RVs accordingly since, they know their Master’s schedule

23. 10.03.2003 presented by Hasan SÖZER23 Scheduling Structure  Scheduling may conceptually be divided into two: Inter-piconet scheduling Intra-piconet scheduling  Intra-piconet scheduler should consider the results of inter-piconet scheduling JUMP mode may inform about which slaves are actually present and which are not

24. 10.03.2003 presented by Hasan SÖZER24 Clock-drift & Power Saving  Because of the clock-drifts, an offset has to be added to the frame numbers calculated PMP nodes can track the clocks in all piconets it participates in and update required offsets accordingly (once every 30 seconds)  Jumping nodes can utilize JUMP mode for power saving

25. 10.03.2003 presented by Hasan SÖZER25 Conclusion  An efficient & flexible scheme  Adaptible to different traffic conditions  Missing RV points may cause defficiencies  Intra-piconet scheduling is also important  Just a framework is defined, no spesific algorithms are given