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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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- 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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- 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
Frequency Assignment (1)
Overview Frequency Assignement
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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
Frequency Assignment (3)
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
Frequency Assignment (4)
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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
Frequency Assignment (5)
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
Frequency Assignment (6)
Unlicensed 2.4 GHz ISM band (2)
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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
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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- 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
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)
Propagation Environment
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)
Propagation Environment
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
Propagation Environment
Other Propagation Effects
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September 2, 2008 19
1. Overview Radio Propagation / Frequency Assignment
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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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
802.15.4 Physical Layer
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
802.15.4 Physical Layer
timeperiod = 60s
current
...
t_SIFSt_LIFS t_LIFS
Nx repeated
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September 2, 2008 23
1. Overview Radio Propagation / Frequency Assignment
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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- 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 [%]
Practical Investigations
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
Practical Investigations
AT86RF212 at 915 MHz Range Measurement
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Practical Investigations
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
Practical Investigations
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
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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Range / Coverage Test Setup
AT86RF212 Range- and Coverage Test Setup
Antenna
RCB Radio Controller
BoardDisplay Board
Software RES
Radio Evaluation Suite (PER)
Range / Coverage Test Setup
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Range / Coverage Test Setup
AT86RF231 Range- and Coverage Test Setup
Antenna
RCB Radio Controller
BoardDisplay Board
Software RES
Radio Evaluation Suite (PER)