Microelectronic Solutions for Water Metering and Monitoring · Microelectronic Solutions for Water...

Prof. Dr.-Ing. Axel Sikora

Dipl.-Ing. Dipl. Wirt.-Ing.

Symposium on Telemetry Systems

for Water Management

1

Microelectronic Solutions for

Water Metering and Monitoring

Prof. Dr.-Ing. Axel Sikora, Dipl.-Ing. Dipl. Wirt.-Ing.

Dipl.-Inform. (FH) Manuel Schappacher

Lab Embedded Systems and Kommunikationselektronik

HS Offenburg





2

Table of Contents

1. introduction & requirements

2. MAC layer approaches

3. network layer approaches

4. application layer approaches

5. water monitoring example

6. status & outlook





3

ch.1.1: introduction – motiviation

• Cyber Physical

Systems (CPS)

• Internet of Things

(IoT)

• Ambient Intelligence

• in practically all

applications

– interesting: vertical

and horizontal (!)

integration

– TeleX Applications





4

ch.1.1: introduction – motiviation

• need of embedded low cost and

low energy communication

• does wireless mean

– „less wires“?

– or „no wires“?

• energy provision is of key

importance for many use cases

• requirement: freedom of maintenance

at least 5 – 10 years

– battery lifetime

– energy harvesting systems





5

ch.1.2: introduction – layer split

• protocol development for energy autarkic systems affects all layers

• L1 (physical layer):

– energy efficient transceivers

– energy efficient modulation schemes

– wakeup technologies

– silicon technologies

• including circuit design (e.g., PLL, wakeup circuits, …)

• L2 (data link layer):

– frame formats

• synchronisation

• sleep modes

– topologies

– network registration & administration





6

ch.1.2: introduction – layer split

– L3 (network layer):

• energy aware / energy efficient routing

– L4 (transport layer) :

• energy efficient retransmissions / reliability

– L7 (application layer):

• data formats

– CoAP or alike

• network administration

• operation schemes





7

ch.2.1: MAC – energy consumption

• energy consumption is of key importance

• power consumption

– practically modern RF transceiver allow „low“ power consumption

– for SRWN mostly identical in TX and RX (!!!) mode

• minimum around 10 mA @ 1,5 … 1.8V

• typical 15 … 20mA @ 1,5 … 1.8V

– TI CC1125: 46 mA @ 3 V @ output power of 16 dBm.

» nearly 29 % efficiency from electrical input power to radiated power at antenna

– Si446x transceivers draw 30 nA in shutdown mode and 50 nA in standby

– TI CC1120 transceivers draw 0.5 µA in timer mode

• reduction of energy consumption with extensive sleeping

– student approach

actstdbyactopmean rIrII 1





8

ch.2.2: MAC – energy consumption – sensor / sender sleeping

• sleeping modes are very practical for many sensor applications – wakeup device by own interrupt

• i/o interrupt

• timer interrupt

– application examples:

• regular sensing, e.g. temperature sensor

– event driven sensing, e.g. light switch

– requires receiver, which is „always on“

• necessity to be mains powered

• receiver can be end or forwarding node

– coordinator, router, „mailbox“

– examples

• EnOcean Radio Protocol

• ZigBee PRO Green Power





9

ch.2.3: MAC – energy consumption – actuator / receiver sleeping –

synchronisation

• problematic use cases: – polled sensors

– actuators

• fire detector & alarm

• access systems

• medical implants

• routing nodes

• in case of sleeping period T – worst case latency T

– average latency T/2

• both sides of the network can sleep – synchronisation

• examples: – Wireless M-Bus EN13757-4 Q-mode (precision timing)





10


sniffing /eWOR – RX sniff mode

RX sniff mode

For battery operated systems the RX current is an important parameter and to increase battery lifetime. RX Sniff Mode

can be used to sniff for RF activity using an ultra-low-power algorithm. By increasing the preamble of the transmitted packet, the

receiver can implement RX Sniff Mode and wake up at an interval that ensures that at least 4 bits of preamble is received. RX

termination based on CS greatly reduces the time in RX and forces the radio back in SLEEP if there is no signal on the air.

Que

lle: C

C112X

/C

C1175 L

ow-P

ower

Hig

h P

erfo

rman

ce

Sub

-1 G

Hz

RF

Tra

nsce

iver

/T

rans

mitte

r –

Use

r‘s

Gui

de





11


sniffing /eWOR – RX termination

RX termination to save current

When implementing the RX Sniff Mode, the radio should

terminate RX as fast as possible if there is no signal on the

air to minimize the current consumption. The radio can

terminate the RX mode in lack of a carrier or in lack of

preamble.

basic RX termination methods

Which RX termination to use (CS or PQT) depends on the

system requirements and the environment the system is

operating in.

Carrier Detection Detecting a carrier takes less time compared to detecting a

preamble and therefore the wake-up timeout may be

shorter. However this can only be applied to a “non-

noisy” network

PQT Detection Detecting a PQT takes longer time compared to detecting

a carrier and the wake-up timeout must be shorter when

RX termination is based on PQT compared to CS.

Que

lle: C

C112x

/C

C120x

RX

Sni

ff M

ode

– s

wra

428a

– O

ctob

er 2

013





12


sniffing /eWOR – RX termination

MCU based RX termination

The MCU terminates RX after a timeout equal to the length

of the preamble and sync word. As seen from the figure, this

leads to an even lower current consumption on the radio, but

the MCU will draw some more current compared to case A

and case B.

Que

lle: C

C112x

/C

C120x

RX

Sni

ff M

ode

– s

wra

428a

– O

ctob

er 2

013





13


sniffing /eWOR – Smart Preamble

decrease power consumption

RX Sniff Mode functionality may dramatically decrease

the average power consumption of a receiver by using

long preamble sequences. Long preamble allows the

receiver to sleep for longer periods of time and still

reliably receive the data payload. When the radio wakes

up and goes into RX it uses CS or PQT termination to

detect if there is a signal. If a signal is found, the radio

waits in RX until the sync word is detected.

Smart-Preamble

While using long preamble sequences allows the radio to

sleep longer, it also means that if it wakes up early in the

preamble it has to stay a long time in RX before sync is

found. Smart-Preamble allows the radio to sleep while

waiting for sync, which greatly reduces the current

consumption

Que

lle: C

C112x

/C

C120x

RX

Sni

ff M

ode

– s

wra

428a

– O

ctob

er 2

013





14


sniffing

• key elements

– fast power up / settling time

• including frequency offset compensation (AFC)

• including automatic gain control (AGC)

• latest transceivers reach tidle → rx = 100 … 200 µs

– partial power up

• e.g. for energy detection only

• e.g. for address detection

– selective wakeup might decrease activity rate and reduce attack possibilities

• example 1:

– Wireless M-Bus EN13757-4 S-mode (stationary mode)

• preamble length 576 bits





15


sample calculation

• sample calculation use sniffing modes

• AMI53000 has activation time < 100µs

– sniffing time can be reduced to ~ 130µs

Iquiescent [A] Itransmission [A] Isniff [A]

AMI53000 2,00E-06 1,74E-02 1,20E-02

MSP430 @1MHz, 3V, 85°C 2,80E-06 3,00E-04 2,80E-06

additional components 5,00E-03 5,00E-03

sum 4,80E-06 2,27E-02 1,70E-02

sniff cycle [s] average current [A]

2 5,90E-06

5 5,24E-06

10 5,02E-06





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ch.2.5: Mobile Communication

• P2P smart metering

(gas & water)

– 5-8a

• measurement and

optimization of

GPRS & UMTS

communication

– indoor / outdoor

– roaming

– daytime

• achieved

optimization of

around 50%





17

ch.3.1: NWL – MAC approaches

• all nodes (intermediate &

end) nodes except the

sender are receivers

• the MAC problem is

scaled to routed networks

– overall synchronisation

– hop by hop

synchronisation

• example Wireless HART





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ch.3.1: NWL – MAC approaches – example 2

• 6LoWPAN





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• hop by hop sniffing





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ch.3.2: NWL – energy aware routing – example 3

• practically all legacy routing protocols perform optimization

of a cost function

• typical parameters for SRWNs

– SNR

– # of hops

– ressources

• energy aware routing includes energy state of the nodes

• In most cases, the following five parameters are regarded:

1. node residual energy,

2. energy for transmission process,

3. energy for reception process,

4. replenishment rate, and

5. activity rate Source: L. Longbi, N.B. Shroff, R. Srikant, Asymptotically optimal energy-aware routing for multihop

wireless networks with renewable energy sources, IEEE/ACM Trans. Netw. 15(5): 1021-1034 (2007).





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ch.3.3: NWL – energy aware routing – project example

• Remote wireless water meter

reading solution based on the

EN 13757 standard, providing

high autonomy, interoperability

and range.





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• objectives

– energy autonomy

– P-mode & Q-mode

(incl. routing)

– energy-aware routing

– tool support





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Fig. 4: data field format for search request; (a) as standardized in [7], (b) as proposed extension

Fig. 5: data field format for search response; (a) as standardized in [7], (b) as proposed extension

Fig. 6: data field format for energy level





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ch.3.4: NWL – energy aware routing – simulation example

• simulation: optimization of topologies

and output power

– including collision probability

0,0125

0,0375

0,0625

0,0875

0,1125

0,1375

0,1625

0,1875

0,2125

0,2375

0,2625

0,2875

0,3125

0,3375

0,3625

0,3875

0,4125

0,4375

0,4625

0,4875

R1

R5

R9

0,00E+00

5,00E-06

1,00E-05

1,50E-05

2,00E-05

2,50E-05

3,00E-05

3,50E-05

r/dPtx,r

0,01

0,1

0,0125

0,0375

0,0625

0,0875

0,1125

0,1375

0,1625

0,1875

0,2125

0,2375

0,2625

0,2875

0,3125

0,3375

0,3625

0,3875

0,4125

0,4375

0,4625

0,4875

R1

R5

R9

0,00E+00

5,00E-06

1,00E-05

1,50E-05

2,00E-05

2,50E-05

3,00E-05

3,50E-05

r/dPtx,r

0,01

0,1

dd

d

r r

d

r/2

r/2

d

r r

d

r/2

r/2

Source: A. Sikora, M. Ostesteanu, "Power Consumption Models for Wireless Grid Networks",

WSEAS Conf., Special Session: Intelligent Systems & Adaptive Control, Venice, 2.-4.11.2005.





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ch.3.5: NWL – routing with unidirectional nodes

• practically all legacy routing protocols start routing process from

the sender node

• extension to EnOcean Radio Protocol (ERP)

– unidirectional senders

– necessity to start routing

process from the receiver

Source: F. Schmidt, W. Heller, D. Rahusen, A. Sikora, V. Groza, "Design and Implementation of a Routing Protocol for Seamless Integration of

Unidirectional Energy-Autarkic Wireless Sensor Nodes", IEEE I²MTC Int'l Instrumentation and Measurement Conference, 2010.





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ch.4: APL

• objectives for energy autarkic systems

– reduce duty cycle for data transmission

→ use simple frame formats

– reduce duty cycle for network management

→ use simple management protocols / small number of simple commands

• general challenge for energy harvesting systems

– need energy for commissioning

– how to fill the reservoir at commissioning?

→ use hybrid systems

energy harvesting for prolongation of life time





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ch.5.1: Wireless Sensor Development for Waterway Monitoring –

Use Case

• flooding 13.05.1999

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• volume flow ca 3600m3 (at Breisach)

source: http://www.hhh-ev.de





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Use Case

• building reservoirs

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mar 2011

jul 2009

jan 2009

source: http://www.hhh-ev.de





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Use Case

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Use Case

• topology &

transversal

profile

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ch.5.3: System Design – Hardware

• relais station

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• measuring point

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ch.5.4: System Design – Firmware

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ch.5.5: System Monitoring Software

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ch.5.5: System Monitoring Software

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ch.5.6: lab test setup

• emutator test bed

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ch.5.6: lab test setup

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ch.5.7: field test setup

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ch.5.7: field test setup

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ch.5.8: field test results

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• Measuring point 1

– 200m LOS

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• Measuring point 2

– 2750m NLOS





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ch.6: status & outlook

• increasing experience with energy harvesters

• increasing experience with wireless network protocols

• increasing performance of semiconductor devices

• increasing opportunities for real product development

• but why are there so few products out yet ???

• major challenges:

– currently very few options for standardized solution

• mostly very application specific

– cost

• continue R&D efforts

• continue standardisation efforts





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Thank you for listening !

Thanks for your participation !

Thanks for the amicable cooperation!

Questions?

[email protected]

Microelectronic Solutions for Water Metering and Monitoring · Microelectronic Solutions for Water...

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