ZigBee Technology

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ZigBee Technology

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Outline

• ZigBee Introduction
• ZigBee Network
• Network Configurations
• Network topology
• Data Transmission
• Power Consumption
• ZigBee protocol stack
• Application layer
• Network layer
• Medium access control layer
• Physical layer
• ZigBee Application

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From Popular Science Magazine
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The IEEE 802 Wireless Space
WWAN
IEEE 802.22
IEEE 802.20
WMAN
WiMax IEEE 802.16
Range
WLAN
WiFi 802.11
ZigBee 802.15.4 15.4c
802.15.3 802.15.3c
Bluetooth 802.15.1
WPAN
0.01
0.1
1
10
100
1000
ZigBee standard uniquely fills a gap for low data
rate applications
Data Rate (Mbps)
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Sensor/Control Network Requirements

• Networks form by themselves, scale to large sizes
  and operate for years without manual intervention
  
• Extremely long battery life (years on AA cell),
• low infrastructure cost (low device setup
  costs)
• low complexity and small size
• Low device data rate and QoS
• Standardized protocols allow multiple vendors to
  interoperate

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ZigBee Alliance Overview-

• Organized as an independent, neutral, nonprofit
  corporation in 2002
• Open and global
• Anyone can join and participate
• Membership is global
• Activity includes
• Specification creation
• Certification and compliance programs
• Branding, market development, and user education

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The ZigBee Promoters
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What is ZigBee

• ZigBee is a wireless communication standard that
  provides a short-range cost effective networking
  capability.
• It has been developed with the emphasis on low
  cost battery powered applications, such as
  building automation, industrial and commercial
  controls, marine wireless, personal healthcare.
• The IEEE and ZigBee Alliance have introduced
  ZigBee to provide the first general standard for
  these applications.

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ZigBee Applications
CONSUMER ELECTRONICS
BUILDING AUTOMATION
security HVAC AMR lighting control access control
TV VCR DVD/CD remote
ZigBee Wireless Control that Simply Works
PC PERIPHERALS
PERSONAL HEALTH CARE
patient monitoring fitness monitoring
mouse keyboard joystick
TELECOM SERVICES
HOME CONTROL
INDUSTRIAL CONTROL
asset mgt process control environmental energy
mgt
security HVAC lighting control access
control irrigation
m-commerce info services object interaction
(Internet of Things)
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ZigBee Advantages

• Low cost
• Low power consumption
• Licence free operation in the 2.4GHz 868MHz and
  915MHz bands
• Hundreds of devices per network
• Network flexibility - Star, Cluster tree or Mesh
  configuration

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ZigBee Radio Layer

• The ZigBee standard utilizes IEEE 802.15.4
  standard as radio layer( MAC and physical layer )
  ?
• Three radio bands are defined
• Global useISM 2.4GHz band with 16 channels and
  data rate of 250kb/s
• USA and Australia915MHz band with 10 channels
  and data rate of 40kb/s
• Europe868MHz band with single channel and data
  rate of 20kb/s?

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Market Comparisons
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ZigBee Device Member

• Three kinds of member in ZigBee network
• Coordinator
• response for initializing, maintaining, and
  controlling the network
• Router
• which have capability to participate in the
  routing procedure
• End Device
• transmit and receive frames through their parent
  node

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ZigBee Device Type

• The ZigBee architecture recognizes two types of
  device
• RFD ( Reduced Function Device )
• The RFD has limited resources and does not allow
  some advanced functions( e.g. routing ) as it is
  a low cost end device solution?
• FFD ( Full Function Device )
• Each ZigBee network has a designated FFD that is
  a network coordinator acts as the administrator
  and takes care of organization of the network?

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ZigBee Network

• The ZigBee network is managed by a network
  coordinator,it can starts the network,takes care
  of the structure and controls the joining and
  leaving of the devices in the network?
• If a device intends to join an existing network
  it has to start network association procedure (
  send an authentication request ) that is answered
  by the coordinator within a predefined time?
• If the device intends to leave the network,the
  device issues a disassociation request?

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Network Association Procedure
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ZigBee Network contd

• Network Configurations
• The IEEE 802.15.4 employs the long 64-bit
  address( IEEE ) and a short 16-bit addresses?
• The short address is assigned by the network
  coordinator when a device joins the network and
  is unique within the given network?
• The short address supports over 65535 nodes per
  network?
• The short address of a network coordinator is
  0x00?
• The network identificator ( PAN ID ) is a 16-bit
  number that is used to distinguish between
  overlaying networks?
• To join a network the device has to know the PAN
  ID of the network it intends to associate?
• The IEEE 802.15.4 MAC enables network association
  and disassociation?

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ZigBee Network contd

• Network Configurations
• The medium access method to the channels is
  carrier sense multiple access with collision
  avoidance ( CSMA-CA ) ?
• The ZigBee uses the direct sequence spread
  spectrum ( DSSS ) modulation method?

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ZigBee Network Topologies
Mesh
Star
ZigBee Coordinator
ZigBee Router
Cluster Tree
ZigBee End Device
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ZigBee Network contd

• Network Topology - ZigBee star topology
• Constructed with one coordinator in the center
  and the end devices?
• The device in the topology can only communicate
  via the network coordinator?
• The start topology is necessary for RFD devices
  as they are not capable of routing?

Network coordinator
Reduced Function Device
Full Function Device
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ZigBee Network contd

• Network Topology
• ZigBee mesh topology
• The ZigBee also supports a mesh
  topology,sometimes called cluster-tree?
• Here the FFD devices in the network may
  communicate without the aid of the network
  coordinator?
• These nodes serves as routers in the
  network,forming a reliable network structure with
  healing abilities?

Network coordinator
Reduced Function Device
Full Function Device
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ZigBee Network contd

• Network Topology
• ZigBee tree topology
• Is a multiple star topoloty with one central node
  that is the ZigBee network coordinator?
• The multiple-hop topology networks must support
  routing,so their network administration is more
  complex?

Network coordinator
Reduced Function Device
Full Function Device
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ZigBee Network contd

• Network Topology
• Star clusters in the mesh topology
• Where only RFD devices participate through a FFD
  router device and of mesh links between the FFD
  devices?
• The star links are necessary for the RFD devices
  in the mesh topology as they are able to
  communicate with a single FFD only?

Network coordinator ( FFD )
Network End Device ( RFD,FFD )
Network Router ( FFD )
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ZigBee Network contd

• Data Transmission
• To allow for real-time transmssions the ZigBee
  there are defined two different data transmission
  mechanisms?
• Non-beacon enabled network
• The standard CSMA/CA takes place
• Any node may start the transmission at any time
  as long as the channel is idle?
• Beacon enabled network
• The nodes are allowed to transmit in predefined
  time slots only?
• The coordinate sends a beacon frame ( superframe
  ) and nodes are expected to synchronize to this
  frame?

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ZigBee Network contd

• Power Consumption
• ZigBee is designed for applications that need to
  transmit small amounts of data while being
  battery powered?
• The architecture of the protocols and the
  hardware is optimized for low power consumption
  of the end device?
• The coordinator and routing devices should not be
  battery powered as these should be able to
  receive and transmit all the time?
• Ex in the star topology
• Device Wake up from power saving mode.
• Receive beacon frame and sends data to the
  coordinator.
• Goes to power saving mode again.
• The coordinator stores data and other end device
  poll for the data the data are delivered.
• Disadvantage the coordinator might lead to
  large RAM needs.

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ZigBee Compliant Platform ZCP
Application
ZDO
App Support (APS)
SSP

NWK
ZigBee Compliant Platform

• Platform certification - ensures all parts of the
  stack other than the application are compliant
  with the ZigBee Standard
• Allows Network interoperability but does not
  imply interoperability at the application layer
• There are currently 30 Compliant Platforms to
  choose from

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Application Profiles
Application
ZDO
App Support (APS)
SSP
NWK
Clusters
Clusters
0 off 1 on 2 scene 1 3 scene 2
0 fan off 1 fan on 2 temp set 3 time set

• Application profiles define what messages are
  sent over the air for a given application
• Devices with the same application profiles
  interoperate end to end
• ZigBee publishes a set of public profiles, but
  vendors may create manufacturer specific ones as
  well

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Manufacturer Specific Profiles
Application

ZDO
App Support (APS)
SSP
Certification testing ensures application does
not interfere with other ZigBee networks
NWK

• Allows a vendor to build specialized products
  with a ZigBee Compliant Platform
• Certification testing ensures their product does
  not harm other ZigBee networks
• Manufacturer specific applications are not
  intended to interoperate at the application layer
• Allows product vendor to use ZigBee language and
  logos on their product

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ZigBee Public Profiles
Application

ZDO
App Support (APS)
SSP
Ensures application conforms to a specific public
application profile
NWK

• Guarantees interoperability between products all
  running the same public application profile
• Product vendors may add additional features to
  the public profiles
• Allows product vendor to use ZigBee language and
  logos on their product

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ZigBee Protocol Stack

• The ZigBee stack forms the upper layers of the
  IEEE 802.15.4 PHY and MAC sub-layer
  specifications?
• ZigBee stack layers include a network layer,an
  application layer and a security service provider
  ( SSP ) ?
• It realizes the network layer ( NWK ) and in the
  application layer provides application support
  sub-layer( APS ) and the ZigBee device object (
  ZDO ) ?
• In the framework are added the user defined
  application objects?

ZigBee standard stack architecture
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ZigBee Protocol Stack contd

• In the ZigBee applications are use several
  principal terms that are explained below
• Attribute represents a data entity that may
  refer to some physical quantity.
• Cluster a set of attributes forms a cluster. It
  described the messages received and transmitted
  by the device. Cluster is identified by a 8-bit
  number and it has to be unique within the given
  profile.
• Device description each device is described by
  a device descriptor. It describes the type of the
  device and the incoming and outcoming messages
  of each endpoint on the device.

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ZigBee Protocol Stack contd

• Endpoint is an application on a physical device
  identified by its address and supports
  application within a single profile. One physical
  device may support several endpoints from
  different profiles. There are up to 240 endpoints
  available on a single device.
• Profile is a set of device descriptions forming
  a reasonable application. The description within
  a profile includes definition of the
  endpoints,message clusters and the services
  provided by the device. Profiles are managed by
  the ZigBee Alliance for allocating the unique
  profile identifier for each profile. The profile
  identifier is a 16-bit number that may be
  obtained from the ZigBee Alliance only.

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ZigBee Protocol Stack contd
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ZigBee Protocol Stack contd

• The profile are the base that enables
  interoperability of device from different vendors
  and even different versions.
• Once the profile is developed it shall be
  submitted to the ZigBee Allicance that will
  allocate the profile identifier.
• The profile to start with when creating an
  application if no suitable existing profile is
  available would be naturally the generic profile.
• Within the profile is the most important part the
  definition of the messages passed between the
  devices and the type of available devices.

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ZigBee Protocol Stack contd
ZigBee device type architecture
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ZigBee Protocol Stack contd

• Application Layer
• The application layer carries the code of the
  individual custom application.
• According to the ZigBee specification this code
  is written into the ZigBee Device Object ( ZDO )
  and the function of the device is specified.
• The application support sublayer ( APS ) forms
  the low level of the application layer.
• Here is the binding and discovery of neighburing
  device handled and also responsible for
  forwarding of message among devices that are not
  able to communicate directly.
• Binding is the ability to match different but
  compatible devices together , such as a switch
  and lamp.

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ZigBee Protocol Stack contd

• Network Layer ( NWK )
• Handles the network level of the communication.
• It is managing the network structure and handles
  routing and security functions for the relayed
  messages.
• The network layer needs to maintain the
  information about the nodes within the network.
• The properties and parameters of the network are
  specified in the application as stack
  configuration of the network layer.

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ZigBee Protocol Stack contd

• Medium Access Control Layer
• Controlling access to the shared radio channel
  and It generates and recognizes the addresses
  ,verifies the frame check sequence.
• The MAC layer is also responsible for the
  scheduling of the frame transmissions in the non
  beacon mode and beacon mode.
• In the non beacon mode using CSMA/CA method. In
  this mode every node listen to the channel prior
  to starting its transmission ( free channel
  assessment ).
• After the channel is found to be free the node
  starts it transmission. When the node suspects a
  collision it quits transmitting and waits for a
  random period to retry.

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ZigBee Protocol Stack contd

• Medium Access Control Layer
• In the beacon mode there is an optional
  superframe structure employed.
• The superframe is started by the beacon and
  followed by 16 equal time slots. The first nine
  slots can be used by any device. The following
  seven slots ( denoted as GTS Guaranteed Time
  Slots ) are reserved and can be allocated by
  individual devices by a request .

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ZigBee Protocol Stack contd
For low-latency application or some requiring
specific data bandwidth
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Synchronize the attached devices Identify the
PAN Describute the structure of the superframe
0?BO?14, 0?SD?14 BOBeacon Order, SOSuperframe
Order
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ZigBee Protocol Stack contd

• Physical Layer
• The physical layer is defined by the IEEE
  802.15.4 standard.
• The modulation of the raw data is managed by DSSS
  modulator.
• According to the standard IEEE 802.15.4 the raw
  data bits are grouped into nibbles ( 4-bit groups
  ) and represent a symbol .
• The 4-bits of nibble make 16 different symbols
  possible .
• There is a look-up table that assigns to each of
  the symbol a 32-bit sequence that is called
  chipping code .
• The chipping codes is presented to the modulator
  that construct the transmitted signal using
  half-sine plus construction .
• In the 2.4Ghz band as physical layer is employed
  the OPQSK .
• On the transceiver side the process is reversed .

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IEEE 802.15.4 PHY Overview Operating Frequency
Bands
2.4835 GHz
Direct sequence Spread spectrum (DSSS)
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Positioning Techniques

• Measurement of Distance

• Time of arrival

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Measuring Distance by RF Signal Strength

• An experiment by IEEE 802.11b

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Positioning by Trilateration

• ideal situation

• real situation

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ZigBee Applications
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ZigBee Home Control
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ZigBee Home Lighting Network
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ZigBee Home Lighting Network
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ZigBee Home Lighting Network
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ZigBee Home Lighting Network
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The ZigBee eco-system adds future value
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