2002/12/27 Chung-Hsien Hsu Bluetooth Location Networks F.J. Gonzalez-Castano, J. Farcia-Reinoso...

2002/12/272002/12/27 Chung-Hsien HsuChung-Hsien Hsu

Bluetooth Location NetworksBluetooth Location Networks

F.J. Gonzalez-Castano, J. Farcia-ReinosoF.J. Gonzalez-Castano, J. Farcia-Reinoso

Departamento de Ingenieria Telematica, Universidad dDepartamento de Ingenieria Telematica, Universidad de Vigoe Vigo

Globecom '02Globecom '02

Speaker: Chung-Hsien HsuSpeaker: Chung-Hsien Hsu


OutlineOutline

IntroductionIntroduction MotivationMotivation BackgroundBackground Bluetooth Location NetworksBluetooth Location Networks

BLN ProtocolsBLN Protocols ConfigurationConfiguration Location ProtocolLocation Protocol Location zonesLocation zones ScalabilityScalability

Performance EvaluationPerformance Evaluation ConclusionsConclusions


Introduction-MotivationIntroduction-Motivation

Proposing a Bluetooth Location Network (BLN) Proposing a Bluetooth Location Network (BLN) for location-aware or context-driven mobile for location-aware or context-driven mobile networks.networks.

Existing service servers that need to know user Existing service servers that need to know user location in real-time, and send context-oriented location in real-time, and send context-oriented information to user handhelds when necessary.information to user handhelds when necessary. M-commerce (mobile e-commerce)M-commerce (mobile e-commerce) Electronic guidance.Electronic guidance.


Introduction-BackgroundIntroduction-Background

Many user-positioning solutions have been Many user-positioning solutions have been proposed:proposed: Based on specialized devices.Based on specialized devices. Not supported by commercially available data Not supported by commercially available data

terminals.terminals.


Introduction-Background (cont.)Introduction-Background (cont.)

Positioning systems supported by commercial Positioning systems supported by commercial terminals:terminals: Cell phone location services and GPS.Cell phone location services and GPS.

Effective for outdoor application.Effective for outdoor application.

HP’s Cooltown.HP’s Cooltown. Based on IR beacons.Based on IR beacons. User-dependent.User-dependent.

( user must aim the infrared port to location beacons.)( user must aim the infrared port to location beacons.)


Introduction-Background (cont.)Introduction-Background (cont.)

User-dependent vs. User-independentUser-dependent vs. User-independent User-independent is only a disadvantage in aggressivUser-independent is only a disadvantage in aggressiv

e systems.e systems. They are complementary.They are complementary.

iPAQ H3870 could use Cooltown to retrieve information on a iPAQ H3870 could use Cooltown to retrieve information on a single object.single object.

Bluetooth-assisted context awareness to retrieve information Bluetooth-assisted context awareness to retrieve information on the surrounding hall.on the surrounding hall.


Introduction-BLNsIntroduction-BLNs

Assumption:Assumption: Users carry a Bluetooth-enabled terminal, or any Users carry a Bluetooth-enabled terminal, or any

mobile data terminal and an independent Bluetooth mobile data terminal and an independent Bluetooth location badge.location badge.

The badge interacts with the BLN, which The badge interacts with the BLN, which provides service servers with real-time user provides service servers with real-time user position.position.


Introduction-BLNs (cont.)Introduction-BLNs (cont.)

Philosophy: establishing a cooperative location network.

User modem addressesBluetooth stations addresses.


Introduction-Motivation (cont.)Introduction-Motivation (cont.)

Advantages of BLN:Advantages of BLN: Transmitting position information to the service Transmitting position information to the service

servers without user participation.servers without user participation. Not subject to line-of-sight constraints.Not subject to line-of-sight constraints. Base technology is supported by existing commercial Base technology is supported by existing commercial

handhelds.handhelds. Admitting alternative uses as a security network when Admitting alternative uses as a security network when

the target area is closed to the public, or as a spare the target area is closed to the public, or as a spare network for emergencies.network for emergencies.


BLN Protocol-ConfigurationBLN Protocol-Configuration

Configuration:Configuration: BLN is composed by mobile badges and static BLN is composed by mobile badges and static

Bluetooth units (SN).Bluetooth units (SN). Using Hexagonal tiling.Using Hexagonal tiling. Any SN has at most seven closest neighbors.Any SN has at most seven closest neighbors. SN units use SN units use Bluetooth inquiry calls to scan their to scan their

surroundings periodically.surroundings periodically.


• All SNs are organized in a radial scatternet around a master node.

BLN Protocol-Configuration (cont.)BLN Protocol-Configuration (cont.)

• SN X-Y : the Bluetooth address of SN Y in layer X.

• Each SN is a slave of all six surrounding neighbor SNs.

Service servers



Rules:Rules: All SNs perform inquiry cycles periodically.All SNs perform inquiry cycles periodically. If SN If SN aa detects an inquiry from SN detects an inquiry from SN bb, and , and bb is not is not

currently listed in currently listed in aa’s routing table.’s routing table. A must send its A must send its minimum distance to the master node to to b.b.

All SN minimum distances are set to All SN minimum distances are set to ∞∞ at power up. at power up. Exception the master node’s, which is set to 0.Exception the master node’s, which is set to 0.

If SN does not receive an answer from one of its If SN does not receive an answer from one of its neighbors that was previously listed in the routing neighbors that was previously listed in the routing table, it deletes the corresponding entry.table, it deletes the corresponding entry.



If change its minimum distance to the master node, thIf change its minimum distance to the master node, the SN transmits a new minimum distance packet to all ie SN transmits a new minimum distance packet to all its slaves.ts slaves.

The routing table stores pairs of neighbor SN addressThe routing table stores pairs of neighbor SN addresses and their distances to the master node.es and their distances to the master node.

Which is sorted by distance.Which is sorted by distance.



Master node

SN1-1

SN2-1

SN1-2

SN1-3

SN2-2

SN2-3

SN2-4

SN2-5

SN3-5

SN3-6

inquiry

SN 2-4SN 2-4

∞∞

SN 1-2SN 1-2 ∞∞

SN 1-3SN 1-3 ∞∞

SN 2-3SN 2-3 ∞∞

SN 2-5SN 2-5 ∞∞

SN 3-6SN 3-6 ∞∞

SN 3-5SN 3-5

∞∞

distance packet

Minimum distance

SN 3-5SN 3-5

∞∞

SN 2-4 ∞



Master node

SN1-1

SN2-1

SN1-2

SN1-3

SN2-2

SN2-3

SN2-4

SN2-5

SN3-5

SN3-6

0

SN 1-2SN 1-2

∞

SN 1-1SN 1-1 ∞∞

SN 1-3SN 1-3 ∞∞

SN 2-2SN 2-2 ∞∞

SN 2-3SN 2-3 ∞∞

SN 2-4SN 2-4 ∞∞

SN 2-4SN 2-4

∞

SN 1-2SN 1-2 ∞∞

SN 1-3SN 1-3 ∞∞

SN 2-3SN 2-3 ∞∞

SN 2-5SN 2-5 ∞∞

SN 3-5SN 3-5 ∞∞

SN 3-6SN 3-6 ∞∞

SN 1-2SN 1-2

1

SN 1-1SN 1-1 ∞∞

SN 1-3SN 1-3 ∞∞

SN 2-2SN 2-2 ∞∞

SN 2-3SN 2-3 ∞∞

SN 2-4SN 2-4 ∞∞

1

SN 2-4SN 2-4

2

SN 1-2SN 1-2 1

SN 1-3SN 1-3 ∞∞

SN 2-3SN 2-3 ∞∞

SN 2-5SN 2-5 ∞∞

SN 3-5SN 3-5 ∞∞

SN 3-6SN 3-6 ∞∞

2



Remark:Remark: A simple authentication handshake avoids connection A simple authentication handshake avoids connection

establishment with invalid Bluetooth modems.establishment with invalid Bluetooth modems. Invalid badges answer inquiry cycles with FHS packet.Invalid badges answer inquiry cycles with FHS packet.

Badges do not try to establish data connections with Badges do not try to establish data connections with SNs.SNs.

Does not violate the seven-slave constraint.Does not violate the seven-slave constraint.


BLN Protocol-Location ProtocolBLN Protocol-Location Protocol

The main goal of the BLN is user tracking.The main goal of the BLN is user tracking. All SNs have to inquiries and collect badge All SNs have to inquiries and collect badge

responses.responses.

The SN detect a badge is in charge of building The SN detect a badge is in charge of building location packets..


BLN Protocol-Location Protocol (cont.)BLN Protocol-Location Protocol (cont.)

BD-3

BD-13

BD-17

BD-3

BD-7

BD-11

BD-19

BT addr. Detected New

BD-3BD-3 NoNo NoNo

BD-7BD-7 NoNo NoNo

BD-11BD-11 NoNo NoNo



BD-7

BD-11


BD-3BD-3 Yes No

BD-7BD-7 No No

BD-11BD-11 No No

BD-13BD-13 Yes No

BD-17BD-17 Yes No

BD-19BD-19 Yes Yes


BD-3BD-3 No No

BD-13BD-13 No No

BD-17BD-17 No No

BD-19BD-19 No No

Master node

Location Packet


BLN Protocol-Location Protocol (cont.)BLN Protocol-Location Protocol (cont.)

Remark:Remark: SN responses to SN inquiry cycles are ignored by the SN responses to SN inquiry cycles are ignored by the

location protocol.location protocol.


BLN Protocol-Location zonesBLN Protocol-Location zones

Do not take signal strength nor signal delay into Do not take signal strength nor signal delay into consideration.consideration.

Location precision depends on the number of Location precision depends on the number of SNs that detect a given badge, and on the range SNs that detect a given badge, and on the range of their modems.of their modems.


BLN Protocol-Location zones BLN Protocol-Location zones (cont.)(cont.)

• Class I zone: only three SNs detect the badge.

• Class II zone: only four SNs detect the badge.

• Class III zone: at the edges of the target area.

• Class IV zone: a single SN.


BLN Protocol-ScalabilityBLN Protocol-Scalability

When the configuration protocol converges to an equilibrium point, the maximum distances to the different master nodes are similar.

The area managed by each master node was inversely proportional to the number of master nodes.


Performance EvaluationPerformance Evaluation

Analyze BLN protocol timings.Analyze BLN protocol timings. The inquiry cycle should last for 10.24 s at most.The inquiry cycle should last for 10.24 s at most. Use the IBM Use the IBM BlueHoc simulator. simulator.

Estimate the worst individual badge response time to Estimate the worst individual badge response time to SN inquiries, as the number of badges grow.SN inquiries, as the number of badges grow.

Calculate location packet hop transfer timings.Calculate location packet hop transfer timings. Use 210-byte DM-5 packets to instead of DM-1 packets.Use 210-byte DM-5 packets to instead of DM-1 packets.


Performance Evaluation (cont.)Performance Evaluation (cont.)


ConclusionsConclusions

BLN has the following characteristics:BLN has the following characteristics: Transmit position information to the service servers without user Transmit position information to the service servers without user

participation.participation. Based on a RF technology available in existing handhelds.Based on a RF technology available in existing handhelds. Can be used as a general-purpose data network.Can be used as a general-purpose data network. Infrastructure consists of small, completely independent BluetootInfrastructure consists of small, completely independent Bluetoot

h nodes.h nodes. The spontaneous topology configuration is scalable, by placing a

s many master nodes as necessary. The BLN can coexist with Bluetooth devices that are not part of t

he location system, such as printers or headphones.


Conclusions (cont.)Conclusions (cont.)

Forthcoming work:Forthcoming work: Study BLN survivability.Study BLN survivability.

2002/12/27 Chung-Hsien Hsu Bluetooth Location Networks F.J. Gonzalez-Castano, J. Farcia-Reinoso...

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