A Fast Handoff Scheme For IP over Bluetooth Sang-Hsu Chung, Hyunsoo Yoon, and Jung-Wan Cho Department of Electrical Engineering & Computer Science Divison.

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

2003/01/282003/01/28 Chung-Hsien HsuChung-Hsien Hsu 33

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.

2003/01/28 Chung-Hsien Hsu 4

Introduction (cont.)

Fixed Bluetooth Device

Assume the scan intervalof a base station is 1.28 sec

2003/01/282003/01/28 Chung-Hsien HsuChung-Hsien Hsu 55

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

2003/01/282003/01/28 Chung-Hsien HsuChung-Hsien Hsu 66

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.

2003/01/282003/01/28 Chung-Hsien HsuChung-Hsien Hsu 77

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.

2003/01/28 Chung-Hsien Hsu 8

Inquiry Access Code

Frequency Hop Synchronization

Device Access Code

Inquiry Procedure

PageProcedure

2003/01/28 Chung-Hsien Hsu 9

Tinquiry = 2 * frequency synchronization delay + random backoff delay

Tpage = frequency synchronization delay

2003/01/282003/01/28 Chung-Hsien HsuChung-Hsien Hsu 1010

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.

2003/01/28 Chung-Hsien Hsu 11

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

2003/01/28 Chung-Hsien Hsu 12

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

2003/01/282003/01/28 Chung-Hsien HsuChung-Hsien Hsu 1313

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.

2003/01/282003/01/28 Chung-Hsien HsuChung-Hsien Hsu 1414

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.

2003/01/282003/01/28 Chung-Hsien HsuChung-Hsien Hsu 1515

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.

2003/01/282003/01/28 Chung-Hsien HsuChung-Hsien Hsu 1616

Simulation analysis (cont.)Simulation analysis (cont.)

2003/01/282003/01/28 Chung-Hsien HsuChung-Hsien Hsu 1717

Simulation analysis (cont.)Simulation analysis (cont.)

2003/01/282003/01/28 Chung-Hsien HsuChung-Hsien Hsu 1818

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