a fast handoff scheme for ip over bluetooth sang-hsu chung, hyunsoo yoon, and jung-wan cho...
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A Fast Handoff Scheme A Fast Handoff Scheme For IP over BluetoothFor IP over Bluetooth
Sang-Hsu Chung, Hyunsoo Yoon, and Jung-Wan ChoSang-Hsu Chung, Hyunsoo Yoon, and Jung-Wan ChoDepartment of Electrical Engineering & Computer Department of Electrical Engineering & Computer
Science Divison of Computer ScienceScience Divison of Computer ScienceKorea Advanced Institute of Science and TechnologyKorea Advanced Institute of Science and Technology
International Conference on Parallel Processing International Conference on Parallel Processing Workshops, 2002 (ICPPW’02)Workshops, 2002 (ICPPW’02)
Speaker : Chung-Hsien HsuSpeaker : Chung-Hsien Hsu
2003/01/282003/01/28 Chung-Hsien HsuChung-Hsien Hsu 22
OutlineOutline
IntroductionIntroduction Communication establishmentCommunication establishment Handoff SchemeHandoff Scheme Simulation analysisSimulation analysis ConclusionsConclusions
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IntroductionIntroduction
BLUEPAC ( BLUEtooth Public ACcess )BLUEPAC ( BLUEtooth Public ACcess ) It is a kind of the indoor network and its structure is It is a kind of the indoor network and its structure is
similar to that of cellular network.similar to that of cellular network. It is designed to support IP over Bluetooth.It is designed to support IP over Bluetooth. Providing users to access to the public network such Providing users to access to the public network such
as the Internet.as the Internet. It can be installed in a public area such as train It can be installed in a public area such as train
stations, airports, and supermarkets.stations, airports, and supermarkets.
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Introduction (cont.)
Fixed Bluetooth Device
Assume the scan intervalof a base station is 1.28 sec
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Introduction (cont.)Introduction (cont.)
Scan IntervalScan Interval The frequency synchronization delay is proportional to The frequency synchronization delay is proportional to
the scan interval of the receiver.the scan interval of the receiver. Bluetooth specification defined three scan intervals:Bluetooth specification defined three scan intervals:
• 10 ms ( continuous scan )10 ms ( continuous scan )• 1.28 sec1.28 sec• 2.56 sec2.56 sec
Receiver
Scan Interval
16 slots
Time
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Introduction (cont.)Introduction (cont.)
Motive:Motive: Short range of Bluetooth arises frequent handoffs.Short range of Bluetooth arises frequent handoffs. Slow handoffs might result in the degradation of the Slow handoffs might result in the degradation of the
network performance.network performance.
The proposed scheme is motivated by the need The proposed scheme is motivated by the need for a fast handoff in BLUEPAC.for a fast handoff in BLUEPAC.
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Connection establishmentConnection establishment
The frequency synchronization between two The frequency synchronization between two devicesdevices Inquiry procedure :Inquiry procedure :
• To obtain the device’s clock and address information.To obtain the device’s clock and address information. Page procedure :Page procedure :
• To establish a connection to other device.To establish a connection to other device.
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Inquiry Access Code
Frequency Hop Synchronization
Device Access Code
Inquiry Procedure
PageProcedure
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Tinquiry = 2 * frequency synchronization delay + random backoff delay
Tpage = frequency synchronization delay
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Handoff SchemeHandoff Scheme
Fundamental idea:Fundamental idea: Base station controller assists a mobile device to Base station controller assists a mobile device to
establish a connection to new base stations by giving establish a connection to new base stations by giving their addresses and clocks.their addresses and clocks.
A mobile device during a handoff has no need for A mobile device during a handoff has no need for inquiring the new base station.inquiring the new base station.
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Mobile device
OldBS
NewBS1
NewBS2BSC
Request msg for neighboring BS infoRequest msg for clock and device addr
Clock and addr
Clock and addrClock and addr
Communication
Handoffdetected
Handoff requestScan request
Start toscan Start to
scan
Ack
AckAck
DAC
DAC
Measuresignal str.
DAC
DAC
FHS
Measuresignal str.& choosethe best
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Mobile device
OldBS
NewBS1
NewBS2BSC
DAC
New connection established
Communication tear-down
Ack
Handoff completed
If # of slaves inexisting piconet <7
Master / slave switch request
Ack
End toscan
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Simulation analysisSimulation analysis
Two network topologies for the simulation.Two network topologies for the simulation.
Mobile devices move to a free direction at speed of 1m/s.
Mobile devices move to a specific direction at speed of 1m/s.
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Simulation analysis (cont.)Simulation analysis (cont.)
Handoff delay :Handoff delay : The delay from when a mobile device detects handoff The delay from when a mobile device detects handoff
till when a mobile device establishes a connection to till when a mobile device establishes a connection to new base station.new base station.
Overhead :Overhead : The ratio of the required time during handoffs and the The ratio of the required time during handoffs and the
total simulation time.total simulation time.
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Simulation analysis (cont.)Simulation analysis (cont.)
AssumeAssume The handoff message is higher priority than data.The handoff message is higher priority than data.
Comparison:Comparison: Daid’s scheme [4]Daid’s scheme [4] The plain inquiry-page procedure.The plain inquiry-page procedure.
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Simulation analysis (cont.)Simulation analysis (cont.)
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Simulation analysis (cont.)Simulation analysis (cont.)
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ConclusionsConclusions
Presented a new scheme for improving the handoff Presented a new scheme for improving the handoff performance in BLUEPAC.performance in BLUEPAC.
In order to reduce handoff delay, the inquiry procedure In order to reduce handoff delay, the inquiry procedure should be invoked as small times as possible.should be invoked as small times as possible.
Base station controller stations aggressively assist a Base station controller stations aggressively assist a mobile device, the mobile device has no need to inquiry mobile device, the mobile device has no need to inquiry the new base stations.the new base stations.
The proposed scheme significantly reduced the handoff The proposed scheme significantly reduced the handoff delay and imposed the very light overhead on the base delay and imposed the very light overhead on the base station.station.
EndEnd