Zigbee
By:
Adel Al-Ghamdi
Yousef Al-Rasheedi
For:
214919
215715
Dr. Adnan Al-Andalusi
OUTLINES
 What is Zigbee?
 Why is Zigbee needed?
 Components of Zigbee
 Network Topologies
 LR-WPAN Architecture
 Zigbee vs. Bluetooth
 Zigbee Applications
What is Zigbee?
 Zigbee technology is a low data rate, low power
consumption, low cost, wireless networking
protocol targeted towards automation and
remote control applications.
 It is a result of the joined forces of Zigbee
Alliance and IEEE.
 Zigbee belongs to IEEE 802.15.4 standard.
Why is Zigbee needed?
 There are a verity of standards that address mid
to high data rates for voice, PC LANs, video, etc.
However, up till now there hasn’t been a
wireless network standard that meets the unique
needs of sensors and control devices.
 Sensors and controls don’t need high bandwidth
but they do need low latency and very low
energy consumption for long battery live.
The 802 Wireless Space
Types of Components

Two types of devices used by Zigbee system:
1. Full- function device (FFD).
2. Reduced-function device (RFD).



The network shall include at least one FFD,
operating as the PAN coordinator.
RFD is intended for applications that are
extremely simple and does not need to send
large amount of data.
FFD can talk to RFDs or FFDs while RFD can
only talk to FFD.
Network Topologies
 Star Topology: the communication is
established between devices and a single
central controller, called the PAN coordinator.
 The PAN coordinator may be main powered
while the devices will most likely be battery
powered.
 Each start network chooses a PAN identifier,
which is not currently used by any other
network within the radio sphere of influence.
This allows each star network to operate
independently.
 Applications that benefit from this topology
include home automation, personal computer
(PC) peripherals, toys and games.
 Peer-to-peer (Mesh) topology: has
also one PAN coordinator. In contrast to
star topology, any device can
communicate with any other device as
long as they are in range of one
another.
 It can be ad hoc, self-organizing and
self-healing network.
 Applications such as industrial control
and monitoring, and wireless sensor
networks.
 Cluster-tree topology: is a special case
of a peer-to-peer network in which most
devices are FFDs and an RFD may
connect to a cluster-tree network as a
leave node at the end of a branch.
 Any of the FFD can act as a coordinator
and provide synchronization services to
other devices and coordinators. Only one
of these coordinators however is the PAN
coordinator.
LR-WPAN Architecture
 The device comprises:




IEEE 802.15.4 PHY
IEEE 802.15.4 MAC
IEEE 802.15.4 NWK
Application Layer
 An IEEE 802.2 logical link control
(LLC) can access the MAC
sublayer through the service
specific convergence sublayer
(SSCS).
IEEE 802.15.4 PHY
Freq band
PHY (MHz)
Modulation
(MHz)
Bit rate
(Kbps)
868
868-868.6
BPSK
20
915
902-928
BPSK
40
2450
2400-2483.5
O-QPSK
250
IEEE 802.15.4 MAC
 Zigbee incorporates a CSMA-CA protocol
 This protocol reduces the probability of
interfering with other users and automatic
retransmission of data ensures robustness.
 By determining when to transmit,
unnecessary clashes are avoided.
Data Transfer
 Information in a Zigbee network is transferred in
packets
 Each packet has a maximum size of 128 bytes,
allowing for a maximum payload of 104 bytes.
 The Zigbee specification supports a maximum
data transfer rate of 250 kbps for a range of up
to 30 meters.
 For priority messages, a guaranteed time slot
mechanism has been incorporated . This allows
high priority messages to be sent across the
network as rapidly as possible.
IEEE 802.15.4 NWK
 The responsibilities of the Zigbee NWK layer
include:
 Starting a network: The ability to successfully
establish a new network.
 Joining and leaving a network: The ability to gain
membership (join) or relinquish membership (leave) a
network.
 Configuring a new device: The ability to sufficiently
configure the stack for operation as required.
Addressing: The ability of a Zigbee coordinator to
assign addresses to devices joining the network.
IEEE 802.15.4 NWK
 Security: applying security to outgoing
frames and removing security to terminating
frames
 Routing: routing frames to their intended
destinations.
Zigbee Routing
 Hierarchical routing strategy
 Uses two strategies
 AODV: Ad Hoc On Demand Distance Vector
 Cluster-Tree Algorithm
Ad Hoc On Demand Distance Vector
 Pure on-demand route acquisition algorithm
 Defines path of message from source to sink
 Nodes that are not on active path don’t maintain
routing information or exchange routing tables
 Primary objectives
 Broadcast discovery packets only when necessary
 Distinguish between local connectivity management
and general topology management
 Disseminate information about local connectivity
changes to neighboring mobile nodes
Cluster-Tree Algorithm
 Forms single/multi cluster tree networks
 Forms self-organizing network with
redundancy and self-repair capabilities
 Nodes select cluster heads and form
clusters in a self-organized manner.
 Self-developed clusters then connect to
each other through a designated Device
(DD)
Zigbee vs. Bluetooth
 Zigbee looks rather like Bluetooth but is
simpler, has a lower data rate and spends
most of its time snoozing a node on a
Zigbee network should be able to run for
six months to two years on just two AA
batteries.
 The operational range of Zigbee is 10-75m
compared to 10m for Bluetooth (without a
power amplifier).
Zigbee vs. Bluetooth
 Zigbee devices talk via small data packet, while
Bluetooth's protocol is more complex since it is
geared towards handling voice, images and file
transfers.
 Zigbee allows up to 254 nodes, while Bluetooth
only allows up to 8 slave nodes.
 When Zigbee node is powered down, it can
wake up and get a packet in around 15 msec
whereas a Bluetooth device would take around
3sec to wake up and respond.
Zigbee Applications
security
HVAC
lighting control
access control
BUILDING
AUTOMATION
patient
monitoring
fitness
monitoring
CONSUMER
ELECTRONICS
TV
VCR
DVD/CD
remote
ZigBee
PERSONAL
HEALTH CARE
asset mgt
process
control
environmental
energy mgt
Wireless Control that
Simply Works
INDUSTRIAL
CONTROL
RESIDENTIAL/
LIGHT
COMMERCIAL
CONTROL
PC &
PERIPHERALS
mouse
keyboard
joystick
security
HVAC
lighting control
access control
lawn & garden irrigation
More Information
ZigBee Alliance Web Site
http://www.ZigBee.org
IEEE 802.15 Web Site
http://www.ieee802.org/15