Master’s Thesis in Computer Systems Engineering

Integration of Positioning Capabilities into an existing active RFID System

Andreas FranzWolfgang JohnPhilipp Nagele

Supervisor: Per-Arne Wiberg

Halmstad, 4th June 2004

Integration of Positioning Capabilities into an existing RFID System

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Overview

• General apsects• Project objectives• System concept• Positioning algorithm• Simulation results• Use case

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Project Objective

• Enhancing the existing RFID system with positioning functionalities

• Designing a concept for - an indoor communication protocol- a positioning algorithm on a central back-end

system• Implementing the proposed algorithm• Proving the feasibility by simulations• Analysing system characteristics

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System Components

• Tag - saves received angular data (AoA)

• Reader- collects data from tags - forwards data to the backend system

• Directional Unit (DU)- provides angular information (AoA)

• Backend system (PC)- computes positioning algorithm

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Communication Protocol

DU 1

DU 2

DU 3

DU 4

f

t21

Tag Memory:

DU 1 | 85° | 1 |DU 2 | 225° | 2 |

Reader

Backend system

45280

85225

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Communication Protocol

DU 1

DU 2

DU 3

DU 4

f

t4321

Tag Memory:

DU 1 | 85° | 1 |DU 2 | 225° | 2 |DU 3 | 46° | 3 |

Reader

Backend system

46281

86226

Integration of Positioning Capabilities into an existing RFID System

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Communication Protocol

DU 1

DU 2

DU 3

DU 4

f

t4321 5 6

Tag Memory:

DU 1 | 85° | 1 |DU 2 | 225° | 2 |DU 3 | 46° | 3 |DU 2 | 227° | 6 |

Reader

Backend system

47

282

87227

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Communication Protocol

DU 1

DU 2

DU 3

DU 4

f

t4321 5 6

Tag Memory:

DU 1 | 85° | 1 |DU 2 | 225° | 2 |DU 3 | 46° | 3 |DU 2 | 227° | 6 |DU 3 | 48° | 7 |DU 4 | 283° | 8 |

Reader

Backend system

48

283

88 228

7 8

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Positioning Algorithm

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Example

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Simulation of the Protocol

• Communication protocol modelled in Matlab

• Modular design- Free DU placement- Variable multipath and propagation effects- Adjustable system parameters

• Optimisation of system parameters• Power consumption• Memory considerations

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Use Case

req. Accuracy

Multipath Effects

DU/ 100m2

Assembling Area

Low -Proximity

Medium 0,375

Warehouse

Medium - Palette

High 0,9375

Loading Zone

High - Goods

Low 3

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Use Case

req. Accuracy

Multipath Effects

DU/ 100m2

Assembling Area

Low -Proximity

Medium 0,375

Warehouse

Medium - Palette

High 0,9375

Loading Zone

High - Goods

Low 3

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Use Case

req. Accuracy

Multipath

DU/ 100m2 Mean Error

Assembling Area

Low Medium 0,375 77.0 cm

Warehouse Medium High 0,9375 55.1 cmLoading Zone High Low 3 20.6 cm

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Conclusion

• Positioning achieved with minor hardware adaptations

• Implementation of a positioning algorithm- Plausibility weighting

• High scalability due to flexible DU placement

• Promising accuracy results for a future experimental setup

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Thank you for your attention!