Research Unit for Integrated Sensor Systems

From Synchronized Clocks to Integrable Networks

Sensor Network Research at the Austrian Academy of Sciences

Thilo Sauter

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Status

• Start in April 2004– One of 60 research entities of the Austrian Academy of

Sciences– Funded by Austrian National Bank and the province of Lower

Austria• 28 researchers in an international team

– Austria, Germany, Russia, Pakistan, Italy, Serbia, China• Intensive cooperation with Vienna University of Technology

– Technology support• Part of “Technopol” Wiener Neustadt

– Research institutes and companies working in – Surface technology– Electrochemistry– Tribology– Microsystems

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Integration – Our Mission

• Functional integration– Signal conditioning and processing– Self diagnosis capabilities and adaptability– Sensor fusion

• System integration– Horizontal and vertical communication – Distributed sensor networks– Networked embedded systems

• Circuit integration– Miniaturization– EMC and energy consumption optimization

• Expert integration– Inclusion of all relevant competencies from the beginning on– Co-operation with external partners to complement own

technology and application know-how

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Areas of Expertise

• Basis for integrative, system-oriented solutions• Focus on system design• Open for cooperations

Sen-sors

Circuit Design

Commu-nication

Modelling

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Operative Approach

• Multi-disciplinary combination of traditionally separated know-how areas– Sensor technology– Microelectronics, integrated circuit design– Embedded systems– Algorithm design, software engineering– Network and communication technology

• Basis for integrative, system-oriented solutions• Focus on system design

– “Closed-loop” (active) sensor principles– Robustness– Transducers, controller structures, and networks optimized for

system integration– System modelling and simulation (analytical, numerical)

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Research Focus and Expertise

• Resonant and inertial sensors– Viscosity measurement– Magnetic field measurement

• Miniaturized thermal sensors– Flow measurement– Thermal conductivity measurement

• Capacitive sensors• Smart sensor system architectures

– Modular FPGA-based system-on-chip architectures

– Signal processing for smart sensors

• Clock synchronization in sensor networks

– Hard- and software support

• Security aspects• Vertical integration

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Clock Synchronization … or how to bring real time into real-time networks…

• Goals– Give all distributed nodes in a network a consistent notion of

time– Make synchronization as accurate as possible

• Applications– Distributed measurement systems– Distributed control systems– Reliable data transmission– Secure data transmission– Network access

• Approach– Measurement of network delays– Minimization of jitter– Time stamping of data packets

on lowest possible layer– IEEE 1588 as common standard

Master Slave

Master Time Slave Time

Delay Request

ST1

ST2MT2

Delay Response

ST3MT3

ST4

1

2

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Accuracy

• Hardware-assisted time stamping at MAC level– High-resolution adder-based clock– FPGA-based evaluation platforms for NIC and switch– 10/100/1000 Base-T support– World record: sub-ns synchronization accuracy– Implementation in standard µP: HyNet

Sync. DriverSync. Driver

PTPPTP

PHYPHY

CSCCSC

IPIP

Device DriverDevice Driver

UDPUDP

MACMAC

MIISMIIS

PHYPHY

CSCCSC

Switch FabricSwitch Fabric

MACMAC

MIISMIIS

PHYPHY

MACMAC

otherother

Jitter

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Robustness

• Deficiencies of IEEE 1588– Master is single point of failure– Long switch-over times

• New approach: Master Group– Democratic group of nodes– Fault tolerant– Some nodes with GPS– Backup nodes

• IEEE1588 Slaves– Synchronized standard compliant– Less traffic between Master

Group speaker and slaves (compared to pure democratic approaches)

• Part of new version of standard

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Security

• No security measures considered in IEEE 1588– Typical for automation networks…

• Security introduces jitter• Ressource limited devices• Handling of intermediate nodes

– Switches, transparent clocks– mixed secure and insecure

• Approach– Vulnerability analysis– Definition of parameters– Minimum sync cycles– Limited set of messages– Implementation– First published results

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Master Network Element Slave

(backup-Master)

(active Master)

Malicous (e.g. byzantine) Master

Malicous Traffic Inserter

Information Flow

(1)

(4)(3)

(6)

(2)

(5)

(7)

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Methodology

• Prototyping– Only reasonable for

a few nodes

– Cost intensive

– Nevertheless needed for proof of concept

• Simulation– Large number of

nodes can be investigated

– High-precision clock synchronization requires adequate (very fine grained) simulation models

– Computational expensive

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Position Determination in Wireless Networks

• Project running since May 2007• Goal: find the position of a (unmodified) node in a WLAN

network• Applications: Sensor Localization, Security, new Services

04/21/23 12

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Method for Localization

• Inverse GPS principle– Works with mobile COTS

devices

• Methodology– Delta measurements– Smart Timing Repeaters

are clock synchronized– 3 ns accuracy

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Scalability and QoS in Mixed Wired/Wireless Networks

• FP7 Project FlexWARE – Flexible Wireless Automation in Real-Time Environments

• QoS across network borders– Deterministic behavior– Timing

guarantees

• Scalability– Dynamic growth– Bandwidth

transparency

• Flexible pathsand roaming– Positioning – Interruption free

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Valve Controller

Zone of uncertain connection

Path A

Alternate Path B

Coverage Area A

Coverage Area B Wireless temperature

sensor

J

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Production goods on cart

Real Time Backbone Network

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Scalability and QoS in Mixed Wired/Wireless Networks

• Network Management– Reservation of real-time

bandwidth– Access lists– Inter-controller

communication– Prescheduled roaming

• Safety and Security– Deterministic cyclic

exchange due to synchronized timeslots

– Seamless roaming and handover

– Execution time– Context-aware reaction

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Integrable Networks – Why?

• Interconnection with application - Vertical Integration– Different resource capabilities

(energy, execution time,...)– Different notion of “real-time”

(layer-specific, just-in-time)– Interconnecting wired and wireless

domains– Scalable protocols

(network size and platform)

• Challenges– Low resources of sensor devices– Extensibility and scalability– Long-time deployment– (Security) management – Costs – Management and configuration

ADC µC

n=0

n=1

n=8

dt

dKv

Integrated Sensor

)(tn NCO

9

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Flexible Integration

• Autonomous software agents– Handling of distributed systems (MES)– Agent system design– Definition and implementation of security strategy

• Resource-efficient agent platform for sensor (like) systems

ERP

Order AgentSupervisor

Resource AgentSupervisorInformation

Collector

Ability Broker

Product DataRepository

ERP

MES

Resource

Field control

Resource

Resource Agent

Resource Agent

Order Agent

Order Agent

Order Agent

Order Agent

Communicationvia ACL

ERP

Order AgentSupervisor

Resource AgentSupervisorInformation

Collector

Product DataRepository

ERP

MES

Resource

Field control

Resource

Resource Agent

Order Agent

Order Agent

Order Agent

Order Agent

Communication via Web Services

Communicationvia ACL

Resource Agent

Ability Broker

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Agent Runtime Environment for RFIT

• Scalable solution• FIPA compliant

communication– Advanced message

handling

– Parallel behavior execution

• Highly optimized for resource-limited hardware

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MTS and ACC

FrameworkC-

Agent

FIPA-compliant Agent

TCP-Queue

Behav. 1 Behav. 2 Behav. n...

TCP-Queue

HTTP

TCP-Queue Message

Templates

TCP-Server

Receiver/Decoder

HTTPHTTPHTTP

TCP-Server

HTTP

Sender/Encoder

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Future Challenges

• Scalable communication protocols

– Comprehensive protocol family instead of heterogeneous networks

– Reduced complexity for network integration

• Mixed parallel secure and non-secure systems– Resource optimized security systems

• Overall topic: power awareness– Optimized transducers– Improved data processing architectures and algorithms– Communication interfaces and networks

• New topic for long-term research: bio-inspired approaches for– Sensors– Data processing– Interfaces and networks

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Thank you for your attention

Thilo.Sauter@oeaw.ac.at