11 Dynfs Presentation NFC2013

Institute for Technical Informatics www.ITI.TUGraz.at

1

Manuel Menghin 2013-02-05

Field Strength Scaling in NFC NFC-DynFS: A way to realize dynamic field strength scaling

during communication

Manuel Menghin1, Norbert Druml1, Christian Steger1, Reinhold Weiss1,

Holger Bock2, Josef Haid2 1 Institute for Technical Informatics, Graz University of Technology, Austria

2 Infineon Technologies Austria AG, Design Center Graz, Austria


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Outline

Introduction / Motivation

Related work

Method

Experimental Results

Conclusion / Outlook

Outline


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Introduction META[:SEC:] [1/6]

Vision of the META[:SEC:]1 project:

1 META[:SEC:] : Mobile Energy-efficient Trustworthy Authentication Systems with Elliptic Curve based SECurity, funded by the Austrian

Federal Ministry for Transport, Innovation, and Technology under the FIT-IT contract FFG 829586. The META[:SEC:] consortium consists

of TU-Graz, Infineon Technologies Austria AG and Enso Detego GmbH.

State of the Art

Reader

Smart CardMETA[:SEC:]

RF Interface

Challenges

Power Shortage

Cost Pressure

System Complexity

Security Requirements

IF SecurityField Strength Scaling

Unoptimized

Chip RF Interface Line-powered Battery-poweredPower & Fault Aware

Mobility

Software


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Introduction Target system [2/6]

Target system: mobile NFC-System Mobile RFID-Reader and one passive transponder

Use case Reading digital business cards (reading data >1k)

cmp Target System and general problem description

Mobile RFID-Reader (e.g., Smart Phone) 0..* Transponder(s) (e.g., Smart Card)

RFID communication (data transfer and

power transfer)

Battery Reader-IC (HF-RFID)

Crypto Core

CPU CPU or Statemachine

RF-Interface (HF-RFID)

Crypto Core

Peripherals (e.g. ISO/IEC 7816)


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Introduction Problem / Motivation [3/6]

Resource constraint mobile reader Battery powered (limited energy)

Transfers power to transponder (smart card)

Saving energy means considering the whole system


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Introduction Problem / Motivation [4/6]

Common countermeasures Component based power optimization (power efficient chips)

Crypto Cores in hardware

Goal: System based power optimization

Reader IC

ARM

Mobile Reader

Smart Card/RFID Tag

SC Chip

Peripherals

MEM

Battery Crypto

Power optimizations Fault analyses Power aware security analyses

Considering the whole system, including the communication channel


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Introduction Approach [5/6]

H-Field commonly static

Required H-Field is dynamic Distance

Current operation (e.g. reading)

Wastage of energy when H-Field is too high

Currently: Scale H-Field to save energy [MenM2012]

Problem: Does not scale H-Field during communication

executing idle

Power Awareness

Static H-Field

Adapted H-Field

Required H-Field

idle

Time [s]

H-F

ield

[H

]


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Introduction Approach [6/6]

Contribution of this publication NFC-DynFS method to save energy

Dynamic field strength scaling during communication

Increase of flexibility

Include the behavior of the user

Adapt the magnetic field to the power consumption of the transponder

NFC-DynFS method to avoid an undersupply

Adapting the magnetic field strength to avoid an undersupply


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Related work

Method



Outline


10


Related work

Power optimization and management Observer Controller [Benini2000]

System based abstraction

Control loop

Power transfer between reader and transponder Technique: Power stepping [Xu2011]

Altering field strength to detect transponders

Technique: Distance bounding [Clulow2006]

Measuring the response time for security issues

[Benini2000]


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Related work

Method



Outline


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Method - Approach [1/3]

Approach Observer-Controller power-managment technique [Benini2000]

Observe

The physical relation factor

The current power consumption of the transponder

Control

The magnetic field strength

Data Transmission Channel

Power Transfer ChannelP

ow

er

Co

nsu

mp

tio

n

Time

Transponder(Tag)

CoilPower Supply Pout

Smart Phone

Reader IC

CoilPin

NFC-DynFS

Fiel

d S

tren

gth

Time Ph

ysic

al R

elat

ion

Fa

cto

r

Time

uses

controls

uses


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Method - Idea [2/3]

Observe physical relation factor Measure power transmission current during communication

Observe power consumption of transponder Every operation is invoked by RFID-Reader and is observed

Control the H-Field Use known threshold values according to operation and physical relation

factor

Field strength gain (Rrel)= A

Thresholds for one operation

Field strength gain (Rrel)= B

Field strength gain (Rrel)= C

Tran

smis

sio

n

curr

ent

Physical relation factor

Transponder undersupplied

Threshold current (ir)Operation A

Thresholds for all operations

Operation B

Operation C

Acquire thresholds for possible field

strength gains

Lookup table for control

Field strength Gain (Rrel)

ABC

Operation AThreshold

current (irthres)x.xxx.xxx.xx

Operation BThreshold

current (irthres)x.xxx.xxx.xx


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Method - Deployment [3/3]

NFC-DynFS (deployment model) Uses a command proxy to know the invoked operations

Senses changes of the physical relation factor on reader side

Controls the H-Field using the Reader-IC

deployment Architecture

Reader Transponder

Hardware and SoftwareFunctional Implementation (Reader)

Hardware and SoftwareFunctional Implemenation (Tag)

NFC-DynFS

PhysicalRelationSensingUnit

FieldStrengthScaler PowerPredictionUnit

+Event: Operation invoked

Near Field

Communication

SendAPDU

+Event: Change of physical

relation factor

ScaleMagneticFieldStrength


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Related work

Method



Outline


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Experimental Results [1/4]

Measurement / Simulation Setup: Simulation: SystemC + Android Emulator

Measurement: Android development board + attached reader


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Case Study Used for the simulation and measurement

Use case of reading a digital business card

Detect Card

Idle/deactivate H-Field

/wait 100 ms/numberOfRetries --

Read Business Card (1 kB)

Close Connection/deactivate H-Field

/wait 100 ms

[no card detected && numberOfRetries > 0]

/set numberOfRetries = 100

[card detected]

[no card detected && numberOfRetries == 0]

/wait 100 ms

Three implementations: NFC-DynFS Simple field strength scaling Without field strength scaling

uses


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Simulation

Needed energy of the system [Norm.]

No field strength scaling

1.00

With simple field strength scaling

0,87

With NFC-DynFS

0.77


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Measurement

Needed energy of the system [Norm.]

No field strength scaling

0.98

With simple field strength scaling

1.00

With NFC-DynFS

0.73


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Related work

Method



Outline


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Conclusion NFC-DynFS improofs simple field strength scaling from [MenM2012]

Adaption to changing physical relation factor

26% lesser energy consumption in case study

NFC-DynFS avoids undersupply of the transponder

Adapts to the physical relation factor

Adapts to the current power consumption

Outlook Field strength scaling for multiple transponders

Solve the issue to faster respond to physical relation factor changes

NFC-DynFS without needing threshold values of the system


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Bibliography

[MenM2012] Menghin, M.; Druml, N.; Steger, C.; Wei, R.; Haid, J.; Holger, B. : The PTF-Determinator: A run-time method used to save energy in

NFC-Systems - in: 4th international EURASIP workshop on RFID technology. (2012), S. 92 98

[Benini2000] Luca Benini and Giovanni de Micheli. 2000. System-level power optimization: techniques and tools. ACM Trans. Des. Autom. Electron.

Syst. 5, 2 (April 2000)

[Xu2011] Xunteng Xu; Lin Gu; Jianping Wang; Guoliang Xing; Shing-Chi Cheung; , "Read More with Less: An Adaptive Approach to Energy-Efficient

RFID Systems," Selected Areas in Communications, IEEE Journal on , vol.29, no.8, pp.1684-1697, September 2011

[Clulow2006] Jolyon Clulow, Gerhard P. Hancke, Markus G. Kuhn, and Tyler Moore. 2006. So near and yet so far: distance-bounding attacks in

wireless networks. In Proceedings of the Third European conference on Security and Privacy in Ad-Hoc and Sensor Networks (ESAS'06)

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Wiley & Sons, Inc., 2003.

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[3] D. Cheng, Z. Wang, and Q. Zhou, Analysis of distance of rfid systems working under 13.56mhz, in Wireless Communications, Networking and Mobile Computing, 2008. WiCOM 08. 4th International Conference on, oct. 2008, pp. 1 3.

[4] E. Rolf and V. Nilsson, Near Field Communication (NFC) for Mobile Phones, in Near Field Communication (NFC) for Mobile Phones, 2006, p. 25.

[5] E. Strommer, M. Jurvansuu, T. Tuikka, A. Ylisaukko-oja, H. Rapakko, and J. Vesterinen, Nfc-enabled wireless charging, in Near Field communication (NFC), 2012 4th International Workshop on, march 2012, pp. 36 41.

[6] C. Moser, L. Thiele, D. Brunelli, and L. Benini, Adaptive power management for environmentally powered systems, Computers, IEEE Transactions on, vol. 59, no. 4, pp. 478 491, april 2010.

[7] C. Bachmann, A. Genser, C. Steger, R. Weiss, and J. Haid, Automated power characterization for run-time power emulation of soc designs, in Digital System Design: Architectures, Methods and Tools (DSD), 2010 13th Euromicro Conference on, sept. 2010, pp. 587 594.

[8] T. Lohmann, M. Schneider, and C. Ruland, Analysis of power constraints for cryptographic algorithms in mid-cost rfid tags, in Smart Card Research and Advanced Applications, ser. Lecture Notes in Computer Science, J. Domingo-Ferrer, J. Posegga, and D. Schreckling, Eds. Springer

Berlin / Heidelberg, 2006, vol. 3928, pp. 278288, 10.1007/1173344720.

[9] O. Unsal and I. Koren, System-level power-aware design techniques in real-time systems, Proceedings of the IEEE, vol. 91, no. 7, pp. 1055 1069, july 2003.

[10] S. Chatterjee, S. Roy, and S. Bandyopadhyay, Hop-efficient and poweroptimized routing strategy in a decentralized mesh network using directional antenna, in Parallel and Distributed Computing, 2006. ISPDC 06. The Fifth International Symposium on, july 2006, pp. 155 160.


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11 Dynfs Presentation NFC2013