Alex Wegznek
Chris Griffis
EEL 4514 Communications System
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ZigBee Overview
Purpose of ZigBee
History of ZigBee
How ZigBee works
Pros & Cons
Regulations & Standards
Stack & Protocol
Comparisons
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Specification for communication protocols
based upon IEEE 802.15.4 standard
Wireless sensor monitoring and control
Designed to be:
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Highly reliable
Cost-effective
Low-power
Highly secure
Low-data rate
http://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=1&ved=0CB8QFjAA&url=http%3A%2F%2Fwww.s
cience.smith.edu%2F~jcardell%2FCourses%2FEGR390%2FReadings%2FZigBeeTutorial.ppt&ei=S45vUL2MIpOY9QS164GADQ&usg=AFQjCNFTM-NOUd01KZbHOteELxu737imrQ
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Provide reliable and cost effective solution for
WPANs
Designed specifically for sensor networking and
automation
Intended to fit on 8-bit microcontrollers with 16
and 32-bit solutions available
Low power leads to extended battery life
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Conceived around 1998
Grew out of the realization that Wi-Fi and
Bluetooth were unsuitable for many applications
The first IEEE 802.15.4 standard was finished in
2003
ZigBee PRO (new standard) was finished in 2007
ZigBee PRO has extra features: multi-casting,
many-to-one routing, and more
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Formed in 1997 with 8 original promoter
companies and now has over 200 members
Maintains and publishes the ZigBee standard
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Home Control
◦ Automation, smart
lighting, security,
temperature control
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Commercial Building
Automation
Wireless Sensor
Networks
Industrial Control
Embedded Sensing
http://www.ti.com/lsds/ti/analog/zigbee.page?DCMP=hpa_rf_general&HQS=NotApplicable+OT+zigbee
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Mesh networking
◦ Ad-hoc network
◦ Nodes can forward data
to other nodes which is
called hopping
◦ Multi-hopping can give
the network extended
range as well as avoid
barriers
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Tree and star routing
also available
Low Power
• Devices have low duty cycle
• No constant contact
• Allows devices to operate for the
entire shelf life of the battery
• Leads to low data rates
• Ideal for sensor networks
Low-Data Rate
• Due to low cost/power
• 250 kbps maximum
• Actual throughput comes
out closer to 25 kbps
• Transceivers are half duplex
– Can only receive or
transmit at one time
http://www.digikey.com/us/en/techzone/energyharvesting/resources/articles/Ultra-Low-Power-MCUs.html
High Level of Security
High Reliability
• National Institute of
Standards and Technology
(NIST) Advanced Encryption
Standard (AES)
• AES-128 bit block cipher
algorithm
• ZigBee both encrypts and
authenticates packets
• Carrier sense multiple
access with collision
avoidance (CSMA-CA)
• 16 bit cyclic redundancy
check (CRC); parity bit
• Mesh network finds route
and acknowledges each hop
• End-to-end data arrival
acknowledgements
Direct-sequence spread spectrum (DSSS)
Binary Phase-Shift Keying
(BPSK)
• 868 and 915 MHz band
• Simplest form of phase shift
keying, also the most robust
• Takes the highest level of
noise/distortion to cause an
incorrect decision by the
demodulator
• Only able to modulate at 1
bit/symbol (slow data rate)
Offset Quadrature Phase-Shift
Keying (OQPSK)
• 2.4 GHz band
• Uses 4 different values of
the phase to transmit
• Offset reduces any
unwanted amplitude
fluctuation
• Transmits twice the data
rate in a given bandwidth as
compared to BPSK
Pros
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High reliability
Low cost
Ultra Low power
Highly secure
Open global standard
Remote operation
Easy to implement
Self healing networks
Cons
– Low data rate
– Relatively small
transmission range if
hopping is not used (1075 m)
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IEEE 802.15.4 low rate WPAN standard
Uses the ISM bands
OQPSK - 2.4GHz band
BPSK – lower bands
250 kbps, 40 kbps, and 20 kbps
http://evolt-ektor.com/zigbee-as-a-wireless-network
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16 channels: 5 MHz of BW each
All 16 channels because low BW protocol
Interference tolerant
Fc = (2350 + (5*ch))MHz
where ch = 11,12,…26
http://www.intechopen.com/books/factory-automation/wireless-sensor-networks-for-networked-manufacturing-systems
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Lower protocol
specifications
IEEE 802.15.4 defines
how to:
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Discover networks
Form & join networks
Change channels
Detect interference
Single hop, broadcast and
data-packet delivery
method
bwrc.eecs.berkeley.edu/people/grad_students/.../zigbee%2
0master.ppt
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Simple Stack – easy for user
Physical layer - direct
sequence, cheap, high
integration
MAC layer – several
topologies, works with many
devices
Network layer – control,
communication, and
monitoring the nodes
http://www.tutorial-reports.com/wireless/zigbee/zigbeearchitecture.php
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MAC and PHY layers are under IEEE control
The physical layer is the circuitry
The MAC layer allows networks to form and for data transfer
ZigBee assures security, multi-hops, and interoperability
ZigBee’s security differs from IEEE 802.15.4
The APS layer has tables to keep track of which nodes it can accept
data from
User only worries about task
ZigBee Wireless Networking, Drew Gislason
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Star, Peer-to-Peer, & Mesh
ZigBee network layer has 3 device types: coordinator,
router, and end device
Network layer deals with network discovery, formation,
address allocation, message routing, network wide security
The APS layer uses the address tables to act as a filter
http://www.tutorial-reports.com/wireless/zigbee/zigbeecharacterstics.php
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Coordinator
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Forms network
Monitor/establish/maintains network
Chooses channel
Acts as the trust center
Can act as a router
Router
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Finds and joins networks
Pushes broadcasts along
Maintains routes
Stores data for sleeping end devices
http://www.zigbee.org/
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End devices
◦ Most often sleeping
◦ Periodically wake to check if
their parent nodes have
anything for them
◦ They perfom their tasks
◦ Send data if necessary
◦ Back to sleep
◦ Orphaned nodes will find new
parents
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Fully reliable hand-shake
data transfer protocol
Error detection and
retransmission
ZigBee communicates
similar to us
◦ Collision avoidance
◦ Cannot listen and talk at
same time
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Designed to minimize time
the radio is on
Beaconing (asleep)
Non-beaconing (always on)
https://docs.zigbee.org/zigbee-docs/dcn/06/docs-06-4513-0000mg-zigbee-network-layer-technical-overview.pdf
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Infrequent, small data packets
Many nodes
Timing is critical
◦ 30 ms to add a new slave
◦ 15 ms to wake up
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Lots of devices
http://www.wirelessdesignmag.com/ShowPR.aspx?PUBCODE=055&ACCT=0
000100&ISSUE=1209&RELTYPE=blog&PRODCODE=000000&PRODLETT=ES&
CommonCount=0
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http://www.tutorial-reports.com/wireless/zigbee/zigbee-architecture.php
http://www.newcircuits.com/article.php?id=tut004
http://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=1&ved
=0CB8QFjAA&url=http%3A%2F%2Fwww.science.smith.edu%2F~jcardell%2FCo
urses%2FEGR390%2FReadings%2FZigBeeTutorial.ppt&ei=S45vUL2MIpOY9QS164GADQ&usg=AFQjCNFTMNOUd01KZbHOteELxu737imrQ
Zigbee.org
bwrc.eecs.berkeley.edu/people/grad_students/.../zigbee%20master.ppt