JUMP Mode
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Transcript of JUMP Mode
10.03.2003 presented 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
10.03.2003 presented by Hasan SÖZER 2
Outline
Introduction Rendezvous Window Distribution Signaling of Presence Scheduling Structure Clock-drift & Power Saving Issues Conclusion
10.03.2003 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
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Introduction (2) ... a tradeoff
Tradeoff concerning switching frequency Frequent: large switching overhead Infrequent: long delays
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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 scatternetNot flexibleChanging topology would lead to renegotiation
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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
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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
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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
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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
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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
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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
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Signaling of Presence (2) ... basics
A Master PMP node does not necessarily have to set up JUMP mode towards its regular, non-PMP slaves
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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
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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
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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
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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
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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
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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
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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
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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
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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
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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