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JUMP Mode

JUMP Mode. A Dynamic Window-based Scheduling Framework for Bluetooth Scatternets Niklas Johansson Fredrik Alriksson Ulf Jönsson Switch Lab, Ericsson Research. Outline. Introduction Rendezvous Window Distribution Signaling of Presence Scheduling Structure

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JUMP Mode

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

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

  3. 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 presented by Hasan SÖZER

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

  5. 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 presented by Hasan SÖZER

  6. 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 presented by Hasan SÖZER

  7. 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 presented by Hasan SÖZER

  8. 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 presented by Hasan SÖZER

  9. Rendezvous Window Distribution (2) ... formation • Time is divided into intervals of Nsf 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 presented by Hasan SÖZER

  10. 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 presented by Hasan SÖZER

  11. 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 presented by Hasan SÖZER

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

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

  14. 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 presented by Hasan SÖZER

  15. 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 presented by Hasan SÖZER

  16. 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 presented by Hasan SÖZER

  17. 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 presented by Hasan SÖZER

  18. 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 presented by Hasan SÖZER

  19. 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 presented by Hasan SÖZER

  20. 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 presented by Hasan SÖZER

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

  22. 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 presented by Hasan SÖZER

  23. 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 presented by Hasan SÖZER

  24. 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 presented by Hasan SÖZER

  25. 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 presented by Hasan SÖZER

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