Toward Precision Agriculture: Building a Soil WetnessMulti-Hop WSN from First Principles

Aggelos Bletsas, Aikaterini Vlachaki, Eleftherios Kampianakis,George Sklivanitis, John Kimionis, Konstadinos Tountas, Megasthenis

Asteris and Panagiotis Markopoulos

Telecom LabDepartment of Electronic and Computer Engineering (ECE)

Technical University of Crete (TUC)

April 5, 2011

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Outline

1 Why

2 What

3 Comparison

4 The BIG picture

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WHY?

Why reinventing the wheel?

Cost reduction: from e120 per WSN node → e20 per node!

Research: Low-cost testbed for telecom research(localization, cognition, mobility, etc).

Research: New sensors, new applications.

Teaching: Telecom Synthesis course.

FUN :)

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Outline

1 Why

2 What

3 Comparison

4 The BIG picture

Bletsas et al. (TUC) Ecosense 2011, Belgrade, Serbia April 5, 2011 4 / 20

WHAT? (Hardware - (1))

iCubes are WSN nodes.

SiLabs C8051F320 MCU.

TI/Chipcon CC2500.

2× AA battery operation.

Custom PCB design.

Emphasis to simplicity andflexibility.

Extension Board (XT) for iCube(power jack, UART, JTAG andMCU pinouts).

iCube + XT = iCube Gateway.

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The Humidity Sensor (Hardware - (2))

Ultra low power (300µA max), low cost (×5 cheaper compared to prior art).

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The iCubes Software

Flexibility of C routinesBOOL send packet(BYTE destination id, bit pack type, bit wait for ack,UINT16 timeout, BYTE max tries, BYTE sn)BOOL receive packet(BYTE *length, BYTE source id, bit type, BYTEpacket acceptance level, UINT16 timeout, BYTE sn)

Over the air programming capability (OTAP) has beendeveloped.

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The WSN application towards water management

Successful iCubes WSN demo set up takinghumidity and temperature measurements(built-in thermistor).

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The Gateway Interface - collected information

Due to simple gateway - PC interface (single UART buffer), developmentof another UI is trivial.

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MAC / Routing

Packet driven multi-hop TDM/FDM routing protocol.

No need for clock synchronization.

Packet-driven with highlyunsynchronized WSN nodes.

Tree-based hierarchy.

Exploiting multiple carriers(one for each subtree).

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Outline

1 Why

2 What

3 Comparison

4 The BIG picture

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Comparison

iCubes cost: ∼ 30e(quantities of 10)Prior art: ∼ 120e(of similar functionality).

Power consumption: comparable to prior art.

iCube humidity sensor is power/cost competitive to commercialproducts.

iCubes development cycle: short(simple C based on structured and embedded programming).

OTAP - capable without the use of RTOS!

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Outline

1 Why

2 What

3 Comparison

4 The BIG picture

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GPRS-enabled WSN gateway

Capability of sending data through GPRS to remote database.

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Renewable energy sources

Solar/Wind power utilization.

Website: http://www.telecom.tuc.gr/∼aggelos/tel412 fall2010/

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Testing Emergency Radio Applications

Perhaps first of a kind collaborativebeamforming demonstration.

Zero-feedback, zero CSIdistributed beamforming.

Ideal for reachbackcommunication in low-cost WSNs.

iC iC iC

WSN iCube nodes

Single transmission

Beamfroming Gain

Low-cost testbed(iCubes and USRP BS).

A. Bletsas, A. Lippman and J.N. Sahalos, “Simple, Zero-Feedback,Distributed Beamforming with Unsynchronized Carriers”, IEEEJournal on Selected Areas of Communications (JSAC), SpecialIssue on Simple Sensor Networking Solutions, Vol. 28, No. 7,

pp.1046-1054, Sept. 2010.

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Backscatter Sensor Networks

Single transistor WSN radio.Ultra low cost.Ultra low power.Ideal for environmental WSNs.Challenge: increase range.

A. Bletsas, A.G. Dimitriou and J.N. Sahalos, “Improving BackscatterRadio Tag Efficiency”, IEEE Transactions on Microwave Theory

and Techniques (MTT), Vol. 58, No.6, pp. 1502-1509, June 2010.

G. Vannucci, A. Bletsas and D. Leigh, “A Software-Defined RadioSystem for Backscatter Sensor Networks”, IEEE Transactions onWireless Communications (TWC), Vol. 7, No. 6, pp. 2170-2179,

June 2008.

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The BIG picture

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Conclusion

WSNs can be low cost, easy, modular and fun!

New disruptive technologies are being developed @ TUC/TelecomLab.

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Thank YOU! Questions?

Eleftherios Kampianakis (kampianakis@gmail.com)

Contact info: Aggelos Bletsas

Assistant ProfessorTelecom LabElectronic & Computer Engineering Dept.Technical University of Crete, Greece

aggelos@telecom.tuc.graggelos@media.mit.edu

website: http://www.telecom.tuc.gr/∼ aggelos

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