ZigBeePresentation - WordPress.com

foamyflumpMobile - Wireless

Nov 21, 2013 (3 years and 6 months ago)

72 views

Alex
Wegznek

Chris Griffis

EEL 4514 Communications System




ZigBee

Overview


Purpose of
ZigBee


History of
ZigBee


How
ZigBee

works


Pros & Cons


Regulations & Standards


Stack & Protocol


Comparisons




Specification for communication protocols
based upon IEEE 802.15.4 standard


Wireless sensor monitoring and control


Designed to be:


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%2FZigBee
-
Tutorial.ppt&ei=S45vUL2MIpOY9QS164GADQ&usg=AFQjCNFTM
-
NOUd01KZbHOteELxu737imrQ


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



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






Formed in 1997 with 8 original promoter
companies and now has over 200 members


Maintains and publishes the ZigBee standard


Home Control


Automation, smart
lighting, security,
temperature control


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


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


Tree and star routing
also available


Low Power

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


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

http://www.digikey.com/us/en/techzone/energy
-
harvesting/resources/articles/Ultra
-
Low
-
Power
-
MCUs.html


National Institute of
Standards and Technology
(NIST) Advanced Encryption
Standard (AES)


AES
-
128 bit block cipher
algorithm


ZigBee both encrypts and
authenticates packets

High Level of Security

High Reliability


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)

Offset Quadrature Phase
-
Shift
Keying (OQPSK)


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)



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


High reliability


Low cost


Ultra Low power


Highly secure


Open global standard


Remote operation


Easy to implement


Self healing networks




Low data rate


Relatively small
transmission range if
hopping is not used (10
-
75 m)

Pros

Cons


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


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


Lower
protocol
specifications


IEEE
802.15.4
defines
how to:


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



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/zigbee
-
architecture.php


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


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/zigbee
-
characterstics.php


Coordinator


F
orms network


Monitor/establish/maintains network


Chooses channel


A
cts as the trust center


C
an act as a router


Router


Finds and joins networks


Pushes broadcasts along


Maintains routes


Stores data for sleeping end devices



http://www.zigbee.org/



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


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


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
-
00
-
00mg
-
zigbee
-
network
-
layer
-
technical
-
overview.pdf


Infrequent, small data packets


Many nodes


Timing is critical


30
ms

to add a new slave


15
ms

to wake up


Lots of devices


http://www.wirelessdesignmag.com/ShowPR.aspx?PUBCODE=055&ACCT=0
000100&ISSUE=1209&RELTYPE=blog&PRODCODE=000000&PRODLETT=ES&
CommonCount=0


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%2FZigBee
-
Tutorial.ppt&ei=S45vUL2MIpOY9QS164GADQ&usg=AFQjCNFTM
-
NOUd01KZbHOteELxu737imrQ


Zigbee.org


bwrc.eecs.berkeley.edu/people/
grad_students
/.../
zigbee
%20master.ppt