Localization with RSSI Method at Wireless Sensor
Networks
Osman Ceylan
Electronics Engineering
PhD Student, Istanbul Technical University, Turkiye
28.10.2009
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Presantation Plan
• Networks−Computer Networks−Wireless Sensor Networks
• Hardware specifications• Advantages
• Localization Problem−Localization techniques−RSSI Method
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Networks• Computer Networks
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Networks• Wireless Sensor Networks
RemoteControl
LocalControl
Event
Event
Nodes
Alternativepath
Sensor area
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Wireless Sensor Networks−Wireless sensor networks and computer
networks are similar.• Able to send/receive data• Internal control unit
−But there are some significant differences.• Very small hardware• Wireless communication
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Hardware Specifications• Hardwares are low power small devices.
− Working with battery for 6-24 months
− Easy installing and carring
• Communicaton is wireless.− Generally uses ISM bands ( Especially 433 MHz and 2.4
GHz)− Low communication range (up to 200 meters at
outdoor)
• Microcontroller is processing unit.− Analog and Digital I/O− Internal RAM, Flash
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Advantages of WSN’s Versus Wireless Computer
Networks• Wireless sensor networks can be designed and
implemented much more bigger than computer
networks easily and cheaply.
• Network organization can be setted up
automatically by the hardwares.
• Hardwares:−Very low power consumption−Very low failure rates
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Localization Problem
• How can we find an object’s exact
position?−Triangulation
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Localization Techniques•GPS
−Only outdoor−1-15 meters error
•GSM−Bad in cities−100 meters error
•Sensor Networs−Ultrasonic Based Systems
•Very High Accuricy (under 5 cm), but very low range (max 10 meters)•Hard setting up•Not user friendly
−RSSI Based Systems•1 meter error
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RSSI Method• Received Signal Strength Indication is a
measurement of the received signals power.
• Radio frequency signals’ power decreases with
the distance:− Loss (dB) = 20log(d)+20log(f)+32.45− d=km, f=MHz
• We know communication frequency and
transmit power.So if we can measure received
signals power’s: We can find the distance d.−Received Power = Transmited power – Path
Loss
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RSSI Method
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Fixed Nodex3,y3
Fixed Nodex2,y2
Fixed Nodex1,y1
Fixed Nodex4,y4
MovingNode
R1
R2
R3R4
Advantages of RSSI Method at Localization
• No directional sensor like ultrasonic systems
• Indoor and outdoor usage
• Data communication and sensor usage at same
hardware
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Difficulties at RSSI Method
• Distance calculation is related RF
signal power at receiver.−Multipath propagation−Fading effects−Bad frontend devices
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Industrial Usage
• Data collection−Sensor datas collecting
• Temperature maps producing
• Tracking and location−Object tracking at production lines−Person tracking at hospitals,
penitentiaries−Animal tracking at farms
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Defence Systems
• Ammunition Tracking in a war or
storage
• Soldier Tracking in a war or trainging
• Detecting ally or enemy
• Data collection−For a person dead/alive−For a object existing/operating/moving
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Team
• Electronics Circuits and Antennas
Design Team−1PHd, 4 BSc
• Embedded Design Team−2 Msc, 6 BSc
• Command-Control Software Design
Team−1 MSc, 4 BSc
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Thanks
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