Design for IoT - ETH Z...38 Resources conflicting Predictability The closer the system works at its...

Computer Engineering and NetworksTechnische Informatik und Kommunikationsnetze

Design for IoT

Lothar ThieleETH Zurich, Computer Engineering and Networks

- Trustable Things -

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Landscape

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© www.braingrid.org© www.openpr.com

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Smart World

physical/biological/socialprocesses

observing influencing

reasoningdecidingbig data

CYBER

•WORLD

•PHYSICAL

•WORLD

Nature

Hardware &Software

Computation

Communication

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Endeavors

in long-term autonomous embedded systems

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Building Automation - Monitoring

© Siemens Building Technologies

Characteristics:

• Certified wireless multihop firedetection system

• High dependability requirements(availability, real-time guarantees)

• Battery-powered with long lifetime

Experience:

• new algorithms, models, methods

• tremendeous engineering effort

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High-Resolution Air Pollution Maps

Application Goal

Trustable high-resolution air quality maps.

Long-term operation.

•O3

•NO2

•CO

•PM0.1

•Public transport vehicles equipped with air quality sensors

•High-resolution air pollution maps

•wearable air qualitysensors

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Mobile stations installed on top of trams in Zurich

• Continuously in operation since April 2012

• Monitor main pollutants and environmental parameters

• PM0.1, O3, CO, NO2, temperature, humidity

• more than 100 million measurements and counting …

High-Resolution Air Pollution

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Wireless Monitoring Technology

allows to quantify mountain phenomena at diverse modalities and scales,

provides information for processunderstanding and modeling

can be used for safety critical applications in an hostile environment.

PermaSenseMonitoring in the Extreme

[Jan Beutel et al.: PermaSense]

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PermaSenseMonitoring in the Extreme

Development of early warning systems

New scientific knowledge

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Camera

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Camera

5 field sites in surveillance

> 6 years autonomous operation

> 1 Billion data points

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Dependability and Trust

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© http://www.satiztpm.it/

© nkonnect

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Dependability and Trust

Society will increasingly depend on the Internet of Things.

Dependability and trust are keyfor societal acceptance.

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Predictability and Dependability

natural hazards desaster management

health factory

surveillance

care

mobility

automation

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Scalingto Billions of Devices

Data

Edge-Fog-Cloud ComputingNetworksStandardsBig Data & Analytics

Energy

Zero Power SystemsEnergy HarvestingApproximate ComputingNear-Threshold ArchitecturesBrain-Like Computing

Trust

Security and Privacy

This Talk

Information

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What are the reasons for low dependability

(or tremendous engineering effort)?

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Reason 1: Resource Constraints

Communication Bandwidth

Memory

Computation Energy

Low Cost Sensors© Adrian Ionescu

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An IoT System View© Luca Benini

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Near-Threshold Multiprocessing – PULP© Luca Benini

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Near-Threshold Multiprocessing – PULP© Luca Benini

803 GOPS/W 60k GOPS/W

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Reason 2: Adaptivity

• Adaptivity and feedback due to

• changes in environment

• user interaction

• switching between (power saving) modes, …

• Typical for applications in

• surveillance

• early warning

• personalized medical and health

• industrial control, …

© Mark Dixon

Event-DrivenBehavior

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Adaptive Behavior

Example: Acoustic sensing of mountain phenomena

1. acoustic events are detected

2. host decides on relevance

3. switching on other sensor modalities

4. high rate sensor data communication

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Resources Dependability

The closer the system works at its resource limits, the less reliable it operates.

conflicting

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Resources Dependability


conflicting

computation

communication

queue

task energy

memory

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Resources Dependabilityconflicting

computation

communication

queue

task energy

memory


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computation

communication

task energy

memoryqueue


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overprovisioningis not an option


Why is this a challenge?

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overprovisioningis not an option


Why is this a challenge?

adaptivity increases non-determinismand requires system-wide coordination

Adaptivity

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System Challengesdependable

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System Challenges

adaptive

low resources

µW

sleep welloperate efficiently

wake-up quicklyswitch gears quickly

dependable

35© http://www.systematic-paris-region.org

Some Design Principles

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Interference

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Resources Predictabilityconflicting

Interference is one of the prominent mechanisms.


Adaptivity

memory demanddepends on total sum

application1

application2

application1

application2

application1

application2

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Adaptivity


application1

application2

CPU1 CPU2

shared resource

shared resources and

communication may couple

time and power domains

with cyclic dependencies


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Adaptivity


application1

application2

CPU1 CPU2

shared resource

shared resources and

communication may couple

time and power domains

with cyclic dependencies

interference from other

modalities lead to cross-

sentivities and necessitate

calibration / sensor fusion

CO2CO

NOx

T

H2O

VOC

O3


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Remove unwanted interference by design.

Interference

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PartitioningTime

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PartitioningTime Space

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What about other properties?

Energy

©Cypress

Clock and Power

© Mentor Graphics

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Example: Wireless Node Platform

BOLTSingle Processor APP COM

Sensor

Interface

Network

Protocol

Sensor

Interface

Network

Protocol

Classic IoT/Sensor Node Architecture

memory

interference

time-

interference

BOLT

Partitioning in Space

clock & power-

interference

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Sensor

Interface

Network

Protocol

Sensor

Interface

Network

Protocol

memory

interference

time-

interference

BOLT

firewall for

BOLT Architecture

clock and power

Classic IoT/Sensor Node Architecture

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Sensor

Interface

Network

Protocol

Sensor

Interface

Network

Protocol

Classic Architecture

memory

interference

time-

interference

BOLT

BOLT Architecture

•Application Processor

•Communication

Processor

•BOLT

[Sutton et al. "Bolt: A stateful processor interconnect.]

Total Sleep Power ≈ 8.1 µW

BOLT Sleep Power ≈ 1.3 µW

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Remove unwanted interference by design.If you can not, bound it.

Interference

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Sensor

Interface

Network

Protocol

Sensor

Interface

Network

Protocol

Classic Architecture

memory

interference

time-

interference

BOLT

firewall for

BOLT Architecture

clock and power

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Sensor

Interface

Network

Protocol

Sensor

Interface

Network

Protocol

BOLT

BOLT Architecture

REQ

ACK

SPI

INDA

MSP430FR5969

DCO

FRAM

R/W

REQ

ACK

SPI

INDA

R/W

SP

I A

GP

IO

PO

RT

3D

MA

0

SP

I C

DM

A1

GP

IO

PO

RT

4

MSP430

CORE

INDC INDC

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Sensor

Interface

Network

Protocol

Sensor

Interface

Network

Protocol

BOLT

BOLT Architecture

REQ

ACK

SPI

INDA

MSP430FR5969

DCO

FRAM

R/W

REQ

ACK

SPI

INDA

R/W

SP

I A

GP

IO

PO

RT

3D

MA

0

SP

I C

DM

A1

GP

IO

PO

RT

4

MSP430

CORE

INDC INDC

Use formal methods to bound

interference.

• Static Timing Analysis

• Hardware Verification

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•UPPAAL Model Checker

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Use formal methods to bound

interference.

• Static Timing Analysis

• Hardware Verification

Predictability

Compostionality

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Remove unwanted interference by design.If you can not, bound it.

If you can not, use it to your advantage.

Interference

Computer Engineering and NetworksTechnische Informatik und Kommunikationsnetze

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Let us look at wireless communication

Long Range Network (LoRa)

[Orestis Georgiou et al: Can LoRa scale? 2016.] [Ferran Adelantado et al: Understanding the Limits of LoRaWAN.

IEEE Comm. 2016]

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Let us look at wireless communication

Wireless Mesh Networks

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Can we expect that this construction works

reliably and efficiently?

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Can we expect that this construction works

reliably and efficiently?

No, it doesn't !

Complex and non-deterministic interference

No chance to provide tight bounds

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Use interference to your advantage

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Synchronous Transmissions

Transmissions are overlappingin time and space.

Nevertheless, the receiver decodesuseful information.

Do not avoid interference but use it to your advantage!

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Interference Management

Make use of interference Partitioning in time

Low Power Wireless Bus

• energy (resource) efficient

• adaptive

• robust and predictable

• provable guarantees[Ferrari et al: Low Power Wireless Bus, 2012.]

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But is the underlying principle competitive?

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Evaluation Scenario

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Evaluation Scenario

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Evaluation Scenario

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Results

The best protocolsuse the design principles just

presented.

This year and the year before.

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Reality or Fiction

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packet losstime synchronization

communication disconnect

buffer overflow

energy harvesting

data analysis

sensor fault

failing interconnects

computing faults

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But: «Sensing in the Extreme» is very special

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High-Resolution Air Pollution Maps

Application Goal

Trustable high-resolution air quality maps.

Long-term operation.

•O3

•NO2

•CO

•PM0.1

•Public transport vehicles equipped with air quality sensors

•High-resolution air pollution maps

•wearable air qualitysensors

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Can We Trust Sensor Readings?

as recommendedby manufacturer

Example: Widely used commercial low-cost NO2 Sensor

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• EPA (United States Environmental ProtectionAgency)

• Community Air Sensor Network (CAIRSENSE) project (2016)

…

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Example: Widely used commercial low-cost NO2 Sensor

after sensor array calibration usinglow-cost ozon, humidity and temperature sensors

[Maag et al: Pre-Deployment Testing, Augmentation and Calibration of Cross-Sensitive Sensors, 2016.]

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We will rely on the IoT Infrastructure.

It should be trustable.

We are in demand of appropriatemodels, design, testing and verification methods.

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ETH Zurich

Computer Engineering and Networks Lab

Geodesy and Geodynamics Lab

Micro and Nanosystems

Federal Office for the Environment

University of Zurich

Department of Geography

EMPA

Natural Resources & Pollutants

Acknowledgements

Current and Previous Contributors:

Jan Beutel, Olga Saukh, Zimu Zhou

Reto da Forno, Andres Gomez, Tonio Gsell, Romain Jacob, Balz Maag, Matthias Meyer, Lukas Sigrist, Mina Soliman, Felix Sutton, Roman Lim, Marco Zimmerling, Bernhard Buchli, David Hasenfratz, Federiuco Ferrari, Matthias Keller, Matthias Woehrle, Andreas Meier, Clemens Moser, Lennart Meier, Philipp Blum

Design for IoT - ETH Z...38 Resources conflicting Predictability The closer the system works at its...

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