In this present communication world
there are numerous high data rate communication standards that are
available, but none of these meet the sensors’ and control devices’
communication standards. These high-data rate communication standards
require low-latency and low-energy consumption even at lower bandwidths.
The available proprietary wireless systems’ Zigbee technology is
low-cost and low-power consumption and its excellent and superb
characteristics makes this communication best suited for several embedded applications, industrial control, and home automation, and so on.
What is Zigbee Technology?
What is Zigbee Technology?
Zigbee communication is specially built
for control and sensor networks on IEEE 802.15.4 standard for wireless
personal area networks (WPANs), and it is the product from Zigbee
alliance. This communication standard
defines physical and Media Access Control (MAC) layers to handle many
devices at low-data rates. These Zigbee’s WPANs operate at 868 MHz,
902-928MHz and 2.4 GHz frequencies. The date rate of 250 kbps is best
suited for periodic as well as intermediate two way transmission of data
between sensors and controllers.
Zigbee Modem
Zigbee is low-cost and low-powered mesh
network widely deployed for controlling and monitoring applications
where it covers 10-100 meters within the range. This communication
system is less expensive and simpler than the other proprietary
short-range wireless sensor networks as Bluetooth and Wi-Fi.
Zigbee supports different network
configurations for master to master or master to slave communications.
And also, it can be operated in different modes as a result the battery
power is conserved. Zigbee networks are extendable with the use of
routers and allow many nodes to interconnect with each other for
building a wider area network.
Zigbee Architecture
Zigbee system structure
Zigbee system structure consists of
three different types of devices such as Zigbee coordinator, Router and
End device. Every Zigbee network must consist of at least one
coordinator which acts as a root and bridge of the network. The
coordinator is responsible for handling and storing the information
while performing receiving and transmitting data operations. Zigbee
routers act as intermediary devices that permit data to pass to and fro
through them to other devices. End devices have limited functionality to
communicate with the parent nodes such that the battery power is saved
as shown in the figure. The number of routers, coordinators and end
devices depends on the type of network such as star, tree and mesh
networks.
Zigbee protocol architecture consists of a stack of various layers where IEEE 802.15.4
is defined by physical and MAC layers while this protocol is completed
by accumulating Zigbee’s own network and application layers.
Zigbee protocol architecture
Physical Layer: This
layer does modulation and demodulation operations up on transmitting and
receiving signals respectively. This layer’s frequency, date rate and
number of channels are given below.
Physical Layer of Zigbee Protocol
MAC Layer: This layer
is responsible for reliable transmission of data by accessing different
networks with the carrier sense multiple access collision avoidance
(CSMA). This also transmits the beacon frames for synchronizing
communication.
Network Layer: This
layer takes care of all network related operations such as network
setup, end device connection and disconnection to network, routing,
device configurations, etc.
Application Support Sub-Layer:
This layer enables the services necessary for Zigbee device object and
application objects to interface with the network layers for data
managing services. This layer is responsible for matching two devices
according to their services and needs.
Application Framework:
It provides two types of data services as key value pair and generic
message services. Generic message is a developer defined structure,
whereas the key value pair is used for getting attributes within the
application objects. ZDO provides an interface between application
objects and APS layer in Zigbee devices. It is responsible for
detecting, initiating and binding other devices to the network.
Zigbee Operating Modes and Its Topologies
Zigbee Communication Operation
Zigbee two way data is transferred in
two modes: Non-beacon mode and Beacon mode. In a beacon mode, the
coordinators and routers continuously monitor active state of incoming
data hence more power is consumed. In this mode, the routers and
coordinators do not sleep because at any time any node can wake up and
communicate. However, it requires more power supply and its overall
power consumption is low because most of the devices are in an inactive
state for over long periods in the network.
In a beacon mode, when there is no data
communication from end devices, then the routers and coordinators enter
into sleep state. Periodically this coordinator wakes up and transmits
the beacons to the routers in the network. These beacon networks are
work for time slots which means, they operate when the communication
needed results in lower duty cycles and longer battery usage. These
beacon and non-beacon modes of Zigbee can manage periodic (sensors
data), intermittent (Light switches) and repetitive data types.
Zigbee Topologies
Zigbee Topologies
Zigbee supports several network
topologies; however, the most commonly used configurations are star,
mesh and cluster tree topologies. Any topology consists of one or more
coordinator. In a star topology, the network consists of one coordinator
which is responsible for initiating and managing the devices over the
network. All other devices are called end devices that directly
communicate with coordinator. This is used in industries where all the
end point devices are needed to communicate with the central controller, and this topology is simple and easy to deploy.
In mesh and tree topologies, the Zigbee
network is extended with several routers where coordinator is
responsible for staring them. These structures allow any device to
communicate with any other adjacent node for providing redundancy to the
data. If any node fails, the information is routed automatically to
other device by these topologies. As the redundancy is the main factor
in industries, hence mesh topology is mostly used. In a cluster-tree
network, each cluster consists of a coordinator with leaf nodes, and
these coordinators are connected to parent coordinator which initiates
the entire network.
Due to the advantages of Zigbee
technology like low cost and low power operating modes and its
topologies, this short range communication technology is best suited for
several applications compared to other proprietary communications, such
as Bluetooth, Wi-Fi, etc. some of these comparisons such as range of
Zigbee, standards, etc., are given below.
Comparison Table of Zigbee
Applications of Zigbee Technology
Applications of Zigbee Technology
Industrial Automation:
In manufacturing and production industries, a communication link
continually monitors various parameters and critical equipments. Hence
Zigbee considerably reduce this communication cost as well as optimizes
the control process for greater reliability.
Home Automation: Zigbee is perfectly suited for controlling home appliances remotely
as a lighting system control, appliance control, heating and cooling
system control, safety equipment operations and control, surveillance,
and so on.
Smart Metering: Zigbee
remote operations in smart metering include energy consumption response,
pricing support, security over power theft, etc.
Smart Grid monitoring: Zigbee operations in this smart grid involve remote temperature monitoring, fault locating, reactive power management, and so on.
This is all about a brief description of
Zigbee technology’s architecture, operations modes, configurations and
applications. We hope that we have given you enough content on this
title, for you to understand it better. We are pioneers in developing
Zigbee based projects. For further help and technical assistance, you
can contact us by commenting below.
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