ERA Local Comms 0209 Zigbee 868

8/14/2019 ERA Local Comms 0209 Zigbee 868

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ATMEL Microcontroller Wireless Solutions

Sascha Beyer

local communication development

An ERA Smart Metering Initiative

IEEE802.15.4IEEE802.15.4IEEE802.15.4IEEE802.15.4

IEEE 802.15.4 / ZigBEE at subIEEE 802.15.4 / ZigBEE at subIEEE 802.15.4 / ZigBEE at subIEEE 802.15.4 / ZigBEE at sub----1 GHz1 GHz1 GHz1 GHz


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September 2, 2008 3

Introduction to WPAN The Wireless Space

The wireless space

0.01 0.1 1 10 100 1000

Range(Meters)

WPAN

WLAN

WMAN

WWAN

Data Rate (Mbps)

LowestPo

werC

onsum

ption


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September 2, 2008 4

- IEEE802.15.4 uses only unlicensed ISM radio bands to ensure a worldwide

acceptance and applicability

1. First generation IEEE802.15.4 solutions are operating at 2.4 GHz

2. Second generation IEEE802.15.4 devices using sub-1GHz ISM bands

868 - 870 MHz: ITU Region 1: e.g. Europe, Middle East,

channel #0; ERP < 25 mW (+13.9 dBm)

902 - 928 MHz: ITU Region 2: e.g. North/South America, also Australia,

channel #1 10 ; EIRP 1.0W (+30.0 dBm)

950 956 MHz: 802.15.4d, Japan, under development

779 787 MHz: 802.15.4c, China, under development

sub-1 GHzrange and limited channel capacity are the biggest BENEFIT

Lower frequency band provides extra link budget at higher sensitivity

Limited channel capacity does not attract data streaming services

Frequency Assignment (1)

Overview Frequency Assignement


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September 2, 2008 5

- IEEE802.15.4 sub-1 GHz Frequency bands and data rates

- Definitions for Japan and China are in separate specifications

Reference: IEEE802.15.4TM-2006, Table 1


Overview Frequency Assignement


6/41September 2, 2008 6

Region 1: ERC/REC 70-3 and Harmonized Standard EN300220

- IEEE802.15.4 assigned channel 0 in 868 band, channel 110 in 915 band

- ERC/REC 70-03 and EN 300 220 allocating 3 bands for ISM usage

Notes

1 868 MHz band BPSK and O-QPSK 400kHz BW

No duty cycle limit applies when LBT is used


1 / y+13.9+6.2868.0 868.6

0.1 / y-1.3 / +5.4-4.5863 870

+4.0 / +8.0

+9.4 / +13.4

[dBm]

Max. TXPower1

0.1 / y+0.8865 - 870

1 / y+6.2865 - 868

%

DutyCycle

or LBT

[dBm/100 kHz][MHz]

Power DensityBand


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LBT Listen Before Talk

- Listen Before Talk can be used to increase duty cycle

- Important Parameters are:TX-off time: >100ms (minimum time between 2 transmissions)

Listen time: 5ms if channel is free at begin of listen interval

5..10ms if channel is busy at start of listen interval

(pseudo-random, 0.5ms step size)

TX-on time: < 1s

TX polling sequence: < 4s

LBT threshold: -87 dBm (TX power < 100 mW, BW = 200kHz)Acknowledge: allowed w/o LBT



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- IEEE802.15.4 assigned channel 11 26 in 2.4 GHz band

- Despite IEEE802.15.4 is a low-power standard, regional regulatory bodies

allow the usage of higher transmit powers

- Europe: up to 100 mW (+20 dBm)

- US: up to 1W (+30 dBm)

- Japan: up to 10 mW/MHz

- The wide bandwidth of 2.4 GHz ISM band is attractive for a growing number ofapplications sharing this band

- Wireless LAN (WLAN, with various flavours like 802.11a|b|g|n)

- Proprietary applications (TV and audio streaming, HID, remote control, )

- Bluetooth (BT, BT-EDR, ULP-BT), Wireless USB, RFID

- Cordless phones

- Microwave ovens

- IEEE802.15.4 provides several mechanisms that enhance coexistence with

other wireless devices


Unlicensed 2.4 GHz ISM band (1)


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- Previous coexistence tests investigating the 2.4 GHz interference situation

demonstrating effects between co-located systems

- Effects on IEEE802.15.4 implementations are

- Blocked channels, packet loss

- Increased latency

- Error floor

- Recommendation to overcome such situations are typically

- Increase physical distance between co-located systems

- Frequency hopping

- ZigBee Specification 2007 introduces channel selection management

- A Network Manager is a device which implements network management

functions , including PAN ID conflict resolution and frequency agility

measurements

- This function adds complexity to a 2.4 GHz, extra effort for observing and

controlling the network


Unlicensed 2.4 GHz ISM band (2)


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September 2, 2008 10

1. Overview Frequency Assignment / Radio Propagation

2. Coexistence / Interference Scenarios3. Propagation Environment

4. Physical Layer Atmel ZigBee Solutions

5. Practical Investigations Coverage, Range

6. Conclusions / Summary

Content

Presentation Overview


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- IEEE802.15.4 / ZigBee mechanisms enhancing coexistence (1):

1. CCA using CS and ED

- Collision avoidance mechanism (CSMA-CA), applied to 2.4G and sub-1 GHz

- ED and LQI are measurements used for CSMA-CA to characterize interference situations

2. Dynamic Channel Selection

- Not required for 868 MHz

- Mandatory for 2.4 GHz requires resources and time, increase power consumption

- ChannelList parameters are to be adapted for varying interference scenarios

- Adaptive Frequency Hopping is not likely to implement due to limited channels (16)

3. Modulations schemes

- 2.4 GHz O-QPSK (sine shaped, MSK equivalent) allows a power-efficient modulation

scheme

- Sub-1 GHz bands using bandwidth limited modulation schemes

- 868 MHz is not affected by adjacent/alternate channel interferences

- 915 MHz has typically a higher selectivity due to narrowband characteristic

Coexistence (1)

Coexistence / Interferences (1)


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- IEEE802.15.4 / ZigBee mechanisms enhancing coexistence (2):

4. Low duty cycle

- IEEE802.15.4 specification is tailored for application with low power and low data rate

- Typical applications are anticipated to run with low duty cycle as well

- A low duty cycle reduces the risk of interferences

- Battery operated devices suffer from increasing duty cycle

5. Channel alignment

- Notrequired for 868 MHz

- Mandatory for 2.4 GHz requires resources and time, increase power consumption

- 2.4 GHz channel alignment reduces the number of available channels significantly

- 4 out of 16 channels in guard bands between 802.11b

- Interferences in guard bands are likely due 802.11 TX side lobes

6. Low transmit power

- Applicable to all 802.15.4 bands

- Sub-1 GHz systems are likely to operate at lower power because of

- Better propagation conditions, and

- Less interferences

Coexistance (2)

Coexistence / Interferences (2)


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1. Overview Radio Propagation / Frequency Assignment





Content



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- A ZigBee network installation requires knowledge about propagation

conditions and environmental interference situations

- A link budgetcalculation is a first estimate to compare IEEE 802.15.4

implementations

- The link budget takes technical parameters of the system into account, like

- Receiver sensitivity

- Transmit Power

- Antenna Gain

- The calculation of a certain path loss requires further knowledge about the

operating frequency of the network

- Operating frequency sub-1 GHz vs. 2.4 GHz

Propagation Environment



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- Exemplary, a comparison between IEEE802.15.4 implementations is shown

to emphasize the effect of different ISM frequency bands

Conclusion: sub-1 GHz adds to IEEE 802.15.4 systems

Increased range due to the lower frequency band, and

increased sensitivity by running a lower data rate

Free Space Propagation (2)


MHz9158688682400Frequency band

26,1

120

-108

40

BPSK

+10

BPSKO-QPSKO-QPSKModulation

4,4

104

-101

100

+3

AT86RF212

km15,51,6Free space range

dB115104Link budget

dBm-110-101Sensitivity

kb/s20250Data Rate

+5 dBm+3TX Power

UnitAT86RF231

x 2.8


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-80

-70

-60

-50

-40

-30

-20

-10

0 5 10 15 20 25 30 35 40 45 50

Distance [m]

Path

Loss[dB]

- A free space model does not assume any impact of reflection, diffraction or

multipath

- Multipath (multi-ray) is a typical scenario for wireless private area networks

- A 1st order multipath model assumes the impact of a ground wave as it is

expected for systems operating in conventional environments

Free Space Propagation (3)


868 MHz

2.4 GHz

- Multipath scenariosshows partly a

significant increase of

the path loss caused

by destructive

characteristic ofvarious signal paths

- 868 MHz is more

robust against signal

degradation

multipath

LOS


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- Phenomena's affecting the wave propagation are:

- Multipath propagation

- Operation of WPANs in buildings is characterized by multipath- Causes of multipath are reflections, refractions and attenuation by walls, furniture

and other equipment

- Effects of multipath are constructive or destructive, phase shift or attenuation

- Effects vary over time by changing the setup or varying operational conditions- Absorption by liquids or gases

- H2O absorbs energy caused by the high molecular dipole moment of the water

molecules, critical for 2.4 GHz operation => water meter operation

Conclusion

A sub-1 GHz WPAN is less affected by

multipath propagation and absorption effects


Other Propagation Effects


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Content



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PHY Implementation Details: 868 MHz vs. 2.4 GHz

802.15.4 Physical Layer

-18

+5

-98

25.8 (0 dBm)

22.31.6

0.03

2.4 GHz

Competition

TX Output Power

RX Sensitivity

Current Consumption

Supported Standards

ISM / proprieatary

802.15.4-2006

802.15.4-2003

dBm+3+11Pout, max

dBm-17-11Pout, min

mA0.40.4Idle

dBm-101-100OQPSK-250

dBm-101OQPSK-100

-110

11.5 (-6 dBm)

9

0.1

AT86RF212

Sub-1 GHz

uA0.02SLEEP

dBmBPSK-20

mA14.3 (+3 dBm)TX (comparable link

budget, 1.55 km)

mA13.5RX

UnitAT86RF231

2.4 GHz


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Sub-1 GHz specifies optional data rates (OQPSK-100) to reduce frame duration

Symbol Times, Frame Duration: 868 MHz vs. 2.4 GHz

s1616OQPSK-250

s25OQPSK-100s50BPSK-20

Symbol Period

868 MHz

AT86RF212

Unit2.4 GHz

AT86RF231


ms4.0641.60.640.0320.16OQPSK-250

ms4.0641.60.640.0320.16OQPSK-250802.15.4 2.4 GHz

802.15.4 868 /915MHz

0.08

0.4

PHR

1

8

20

PSDU Duration

2.5

20

50 127SHR

ms6.350.25OQPSK-100

ms50.82BPSK-20

Header Duration Unit

+56%


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- 2.4 GHz need for channel search algorithm, increased data rate and

restrictive timing requirements will balance the difference

PHY Power Consumption / Life Time: 868 MHz vs. 2.4 GHz

0

1,56104

+3

4

2.4 GHz

AT86RF231

km1,391,55Distance

%-41-4,7Life Time Difference

Relative Life Time (PSDU = 127 octets), MCU typ. 2.5mA active

dB10395PathLoss

dBm+5-6Pout

42CSMA-CA cycles

868 MHz OQPSK100

AT86RF212

Unit2.4 GHz

Competition


timeperiod = 60s

current

...

t_SIFSt_LIFS t_LIFS

Nx repeated


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Content



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- Beside link budget calculations real

measurements are performed to demonstrate the

performance of low-power, high performance

IEE802.15.4 transceivers

- A typical battery operated node consist of

- The radio transceiver

- The microcontroller

- The antenna I/F

- Interfaces

Practical Investigations

IEEE802.15.4 Transceiver AT86RF212 sub-1 GHz (1)


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2.4 GHz868 MHzFrequency

OQPSK-250OQPSK-100BPSK-20Modulation

#11#0#0Channel

100

1.4

0

0.16

0 00P2 P4

1002.9P2 P8

1000P2 P7

7.60P2 P6

9.40.34P2 P5

AT86RF212 AT86RF231PER [%]


AT86RF212 at 868 MHz Indoor Coverage (Office)

P2

P5

Elevator

P8

Building 5 floors + garageSide view

4F

3F

0

G

Building 5 floors + garageTop view

Staircase

P6

P7

2F

1F

P2

P4 P5

Ele.P8

P6/7

13m

13m

P4

Office BuildingPTX = +3 dBmPSDU = 20 octets# Frames = 10.000


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- Line of Sight measurement to illustrate the

potential of sub-1 GHz operation


AT86RF212 at 915 MHz Range Measurement


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IEEE802.15.4 Transceiver AT86RF212 915 MHz (2)- Range test measurements are based on packet-

error rate (PER 1%) measurements

- The environment chosen for this test is mainly

characterized by one direct line-of-sight and a

ground wave

- The distance achieved during this test is about

D ~ 4370 m

- Range may be extended using optimized

antennas

- Data rate: 20 kb/s, 20 octets

- Modulation: BPSK-20

- TX power: +10 dBm

- Antenna height: 1.4m


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- Beside link budget calculations real

measurements are performed to demonstrate the

performance of low-power, high performance

IEE802.15.4 transceivers

- A typical battery operated node consist of

- The radio transceiver

- The microcontroller

- The antenna

- Interfaces


IEEE802.15.4 Transceiver AT86RF230/1 2.4 GHz (1)


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C l i / S


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With IEEE 802.15.4 consider BOTH sides of the medal

sub-1 GHz AND 2.4 GHz

ATMELs subsub--1 GHz1 GHz 802.15.4 / ZigBee solutions provide

Longest Range due to low frequency bands

Up to 16 dB improved Link Budget

Leading edge Sensitivity values for all rates

Lowest Power Consumption

MAC features implemented in hardware

Ensures robust and reliable network performance

Pin and functional compatible to 2.4 GHz solutions

No need for amplification

Conclusions / Summary

Wid S l ti f Wi l S l ti


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Wide Selection of Wireless Solutions

Choice of various PHY Implementations

Supported frequency bands- IEEE 802.15.4 at 2.4 GHz

- IEEE 802.15.4 at 868 MHz

- IEEE 802.15.4 at 915 MHz

- Other sub-1 GHz in design

Pin and feature compatible family

2.4 GHz / sub-1 GHz Single Chip Solutions

Wireless Family will grow in various directions!

AT86RF230 AT86RF231 AT86RF212 ATmega128RFA1 ...

IEEE 802.15.4 LeadingIEEE 802.15.4 Leading--Edge Solutions fromEdge Solutions from

ATMELATMEL Microcontroller Wireless SolutionsMicrocontroller Wireless Solutions

Wid S l ti f Mi t ll


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Wide Selection of Microcontrollers

Choice of 100+ AVRs

Devices range from 1 to 512 kB

Pin count range from 8 to 100

Full code compatibility

Pin/feature compatible families

One set of development tools

Supports simple point point -> Fullblown ZigBeemesh networks on one PCB

- Example: ATmega164P, ATmega324P, ATmega644Pand ATmega1284P

= microcontroller optimized for ANY wireless applications

C l i / S


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Software Support

Transceiver adaption layer, access toolbox

IEEE802.15.4 MAC and security

ZigBee stack, ZigBee profiles (e.g. SmartEnergy)

Implementations are for all frequency bands

Implementations available for various MCUs Other stacks are available too, e.g. 6LoWPAN

Conclusions / Summary

Conclusions


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Conclusions

Thank you for your attention!

Resources


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Resources

Technical Support Center

support.atmel.no

Datasheets and application notes

www.atmel.com/products/ZigBee

Other resources

www.avrfreaks.net

www.zigbee.org www.6lowpan.net

News and online trainings

www.avrtv.com

Support by MCU and RF experts

[email protected]

Contacts


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Magnus Pedersen

Director Marketing

Microcontroller Wireless Solutions

Atmel Norway A/S

Vestre Rosten 78Tiller N-7075

Norway

Phone: +47 7289 7647

Cell: +47 928 84579mailto: [email protected]

Contacts

Marketing & Technical ContactsMarketing & Technical ContactsMarketing & Technical ContactsMarketing & Technical Contacts

Sascha Beyer

System Design

Microcontroller Wireless Solutions

Atmel Germany GmbH

Design Center DresdenKnigsbrcker Strasse 61

01099 Dresden

Phone: +49 351 6523-410

Fax: +49 351 6523-5410mailto: [email protected]

Marketing ContactMarketing ContactMarketing ContactMarketing Contact Engineering ContactEngineering ContactEngineering ContactEngineering Contact


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Backup


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Backup

Backup

Range / Coverage Test Setup


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AT86RF212 Range- and Coverage Test Setup

Antenna

RCB Radio Controller

BoardDisplay Board

Software RES

Radio Evaluation Suite (PER)



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AT86RF231 Range- and Coverage Test Setup

Antenna

RCB Radio Controller

BoardDisplay Board

Software RES

Radio Evaluation Suite (PER)

Documents

ERA Local Comms 0209 Zigbee 868