JUMP Mode – A Dynamic Window-based Scheduling Framework for Bluetooth Scatternets Niklas Johansson, Fredrik Alriksson, Ulf J ö nsson ACM 2001 CNF

Outline Introduction Introduction Jump mode Jump mode Rendezvous Window Distribution Rendezvous Window Distribution Signaling of Presence Signaling of Presence Basic signaling scheme Basic signaling scheme Jumping Slave signaling Jumping Slave signaling Jumping Master signaling Jumping Master signaling Directly connected Jumping nodes Directly connected Jumping nodes Conclusion Conclusion

Introduction A piconet has a Master A piconet has a Master Communication only take place between a Master and a Slave Communication only take place between a Master and a Slave A Bluetooth unit can be a Master in only one piconet A Bluetooth unit can be a Master in only one piconet Participant in Multiple Piconet(PMP) node Participant in Multiple Piconet(PMP) node A unit belongs to more than one piconet A unit belongs to more than one piconet

Introduction(cont.) Inter-piconet scheduling (IPS) Inter-piconet scheduling (IPS) A PMP node may only be present A PMP node may only be present in one piconet at a single point in time PMP nodes have to switch between piconets on a time division basis PMP nodes have to switch between piconets on a time division basis Intra-piconet scheduling Intra-piconet scheduling Control the Master ’ s polling of its Slaves Control the Master ’ s polling of its Slaves piconet1piconet2 slaveA

Introduction(cont.) Performance constraint Performance constraint Different piconets are not synchronized in time, there is some overhead related to the switching from one piconet to another Different piconets are not synchronized in time, there is some overhead related to the switching from one piconet to another Tradeoff between bandwidth usage and delay Tradeoff between bandwidth usage and delay Piconet switching times Piconet switching times Many-overhead Many-overhead Few-delay Few-delay

Introduction(cont.) piconet1 piconet2 piconet3

Jump mode - Rendezvous Window Distribution Jump mode Jump mode Presence Presence Absence Absence Not specified Not specified Jumping node Jumping node Master or Slave in Jump mode Master or Slave in Jump mode Peer node Peer node The nodes that a PMP node is connected to The nodes that a PMP node is connected to The jumping node is absent by default assumption The jumping node is absent by default assumption The jumping node has to signal to the peer node when it wants to be present to the link The jumping node has to signal to the peer node when it wants to be present to the link piconet1piconet2 slaveA

Jump mode - Rendezvous Window Distribution

The reason for using RV windows of pseudo random length is to avoid The reason for using RV windows of pseudo random length is to avoid Systematically colliding RV point Systematically colliding RV point Live-lock Live-lock Starvation Starvation Schedule Schedule RV windows of pseudo random length is used RV windows of pseudo random length is used Jumping node use the same sequence of RV windows in all its piconets Jumping node use the same sequence of RV windows in all its piconets RV windows are defined as the distance between two RV points RV windows are defined as the distance between two RV points

Jump mode - Basic Signaling Scheme Jumping slave Jumping slave Set up Jump Mode on all of the links Set up Jump Mode on all of the links Select which piconet to present Select which piconet to present Master will poll the Slave at its RV points Master will poll the Slave at its RV points It has to signal about its presence during a RV window at the occurrence of the RV point It has to signal about its presence during a RV window at the occurrence of the RV point If a PMP is a Master, it does not have to set up Jump Mode If a PMP is a Master, it does not have to set up Jump Mode It can always go back and communicate with its regular, non PMP slaves if fails to signal about its present in another piconet It can always go back and communicate with its regular, non PMP slaves if fails to signal about its present in another piconet piconet1piconet2 slaveA

Jump mode - Basic Signaling Scheme

Jump mode - Jumping Slave Signaling Long-term schedule Long-term schedule To reduce To reduce The number of RV points The number of RV points The number of Master ’ s polling The number of Master ’ s polling The overhead The overhead A Slave pre-allocates a number of RV windows A Slave pre-allocates a number of RV windows Signal this to the Masters Signal this to the Masters Master does not have to poll the jumping Slave at the slave ’ s RV Master does not have to poll the jumping Slave at the slave ’ s RV

Jump mode - Jumping Slave Signaling A triggering event to switch from the basic signaling scheme to long-term scheduling scheme might be the number of failed RV points A triggering event to switch from the basic signaling scheme to long-term scheduling scheme might be the number of failed RV points The drawback is that the flexibility is lost The drawback is that the flexibility is lost

Jump mode - Jumping Slave Signaling Mixed long-term schedule Mixed long-term schedule Some RV windows can be assign to certain piconets whereas the others are assigned to others Some RV windows can be assign to certain piconets whereas the others are assigned to others

Jump mode - Jumping Master Signaling How a Master that is also acting as a PMP node can signal about its presence and absence to its connected Slaves How a Master that is also acting as a PMP node can signal about its presence and absence to its connected Slaves Power – consumption Power – consumption If the regular Slave knows when the jumping Master is absent, it can save power during these time periods If the regular Slave knows when the jumping Master is absent, it can save power during these time periods The Master sends a broadcast at its RV point The Master sends a broadcast at its RV point The drawback is that the jumping Master cannot not know whether the Slaves got the information or not The drawback is that the jumping Master cannot not know whether the Slaves got the information or not

Jump mode - Directly Connected Jumping Nodes One of the jumping node will act as a Master towards the other jumping node One of the jumping node will act as a Master towards the other jumping node The RV windows of both jumping nodes will not match each other The RV windows of both jumping nodes will not match each other Some bandwidth will be lost Some bandwidth will be lost

Jump mode - Directly Connected Jumping Nodes

Conclusion Jump mode framework is presented to facilitate inter-piconet scheduling Jump mode framework is presented to facilitate inter-piconet scheduling Power saving is incorporated in the scheme Power saving is incorporated in the scheme Flexibility is offered for a node to adapt its piconet switching to the traffic condition Flexibility is offered for a node to adapt its piconet switching to the traffic condition

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