Scatternet Formation of BluetoScatternet Formation of Bluetooth Ad Hoc Networksoth Ad Hoc Networks

Bin Zhen, Jonghun Park, Yongsuk KimBin Zhen, Jonghun Park, Yongsuk Kim

HICSS 2003HICSS 2003

OutlineOutline

Scenarios and questionsScenarios and questionsBluetooth and 802.11 protocol stackBluetooth and 802.11 protocol stackBlue-Star island network formationBlue-Star island network formationMeasurement metricsMeasurement metricsSimulation resultsSimulation resultsDiscussion and conclusionDiscussion and conclusion

ScenariosScenarios

File share systemFile share systemConference roomConference room

File transferFile transferUnicast or multicastUnicast or multicast

Service discoveryService discoveryMouse + notebook + APMouse + notebook + AP

Some QuestionsSome Questions

What is the relation between network routiWhat is the relation between network routing and network formation?ng and network formation?Routing protocol mainly consider how many hRouting protocol mainly consider how many h

ops between source and destinationops between source and destination In bluetooth, less number of piconetIn bluetooth, less number of piconet

Less neighbor piconet overlapLess neighbor piconet overlapMore intra-piconet scheduleMore intra-piconet schedule

View of Routing and Network View of Routing and Network FormationFormation

3 hops3 piconets

3 hops2 piconets

802.11 Protocol Stack802.11 Protocol Stack

Bluetooth Protocol StackBluetooth Protocol Stack

A Simplified BT Protocol StackA Simplified BT Protocol Stack

Blue-Star Island Network Blue-Star Island Network Formation(1/2)Formation(1/2)

1.1. All nodes are self-organized, multiple All nodes are self-organized, multiple isolated “blue-star islands” maybe isolated “blue-star islands” maybe formedformed

Blue-Star Island Network FormationBlue-Star Island Network Formation(2/2)(2/2)

2.2. If a slave receive a RREQ message from If a slave receive a RREQ message from another nodes, it check if the destination another nodes, it check if the destination is in its reachable rangeis in its reachable range

If it is yes, RREP will send along the If it is yes, RREP will send along the backward path to sourcebackward path to source

If it is no, the node generate “If it is no, the node generate “Routing Routing TriggerTrigger” to inform all reachable slave to seek ” to inform all reachable slave to seek the neighbor “blue-star island”the neighbor “blue-star island”

Measurement Metrics(1/2)Measurement Metrics(1/2) The procedure of network establishment The procedure of network establishment

and maintenanceand maintenanceTime complexityTime complexity

The time of network convergence to a steady state, The time of network convergence to a steady state, also denote network recovery time due to mobilityalso denote network recovery time due to mobility

Message complexityMessage complexityThe number of packets sent between nodes in The number of packets sent between nodes in

network establish, maintenance and recoverynetwork establish, maintenance and recovery

Network robustnessNetwork robustnessThe impact of local topology change to the total The impact of local topology change to the total

network, loop free network is easy routing, but it is network, loop free network is easy routing, but it is sensitive to movement of some key pointssensitive to movement of some key points

Measurement Metrics(2/2)Measurement Metrics(2/2)

The metrics of communication efficiencyThe metrics of communication efficiencyPacket latency and latency variancePacket latency and latency variance

Relate to all underlying factors, routing algorithm, iRelate to all underlying factors, routing algorithm, inter-piconet, intra-piconet schedule algorithm and nter-piconet, intra-piconet schedule algorithm and network topologynetwork topology

Network diameterNetwork diameterNumber of hops, loop free network makes more hoNumber of hops, loop free network makes more ho

ps, because of the existence of key nodeps, because of the existence of key node

Number of piconetNumber of piconetThe less the number of piconet is, the less packet The less the number of piconet is, the less packet

collision probability iscollision probability is

Simulation Results(1/3)Simulation Results(1/3)

Simulation Results(2/3)Simulation Results(2/3)

Simulation Results(3/3)Simulation Results(3/3)

Conclusion and Discussion(1/2)Conclusion and Discussion(1/2)

To provide an always ready BT ad hoc netTo provide an always ready BT ad hoc network with consideration on piconet number,work with consideration on piconet number, battery power and network maintenance c battery power and network maintenance costost

Loop-free network has 3 main drawbacksLoop-free network has 3 main drawbacksRoot becomes bottleneck of the routeRoot becomes bottleneck of the routeNeed more time on maintenanceNeed more time on maintenancePower consumption is largerPower consumption is larger

Conclusion and Discussion(2/2)Conclusion and Discussion(2/2)

The worst case is that all the “blue-star islaThe worst case is that all the “blue-star islands” are piconets, a tree style scatternet hnds” are piconets, a tree style scatternet has to be formedas to be formed

The best case is that all node aggregate in The best case is that all node aggregate in a single “blue-star island”a single “blue-star island”

The concept of “The concept of “routing triggerrouting trigger” can also b” can also be used in the ad hoc mode of HyperLAN2 e used in the ad hoc mode of HyperLAN2 (because of it is connection oriented)(because of it is connection oriented)

Thank YouThank You