Zigbee Protocol Architecture
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 architecture is a combination of 6 layers.
The Application layer is present at the user level.
The Application Interface Layer, Security Layer, and Network Layer are the Zigbee Alliance and they are used to store data and they use the stack.
Medium Access control and the Physical layer are the IEEE 802.15.4
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.
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.
Above the physical and MAC layers defined by 802.15.4, the ZigBee standard itself defines the upper layers of the system.
This includes many aspects including the messaging, the configurations that can be used, along with security aspects and the application profile layers.
There are three different network topologies that are supported by ZigBee, namely the star, mesh and cluster tree or hybrid networks.
Each has its own advantages and can be used to advantage in different situations.
The star network is commonly used, having the advantage of simplicity.
As the name suggests it is formed in a star configuration with outlying nodes communicating with a central node.
Mesh or peer to peer networks enable high degrees of reliability to be obtained.
They consist of a variety of nodes placed as needed, and nodes within range being able to communicate with each other to form a mesh.
Messages may be routed across the network using the different stations as relays.
There is usually a choice of routes that can be used and this makes the network very robust.
If interference is present on one section of a network, then another can be used instead.
Finally there is what is known as a cluster tree network.
This is essentially a combination of star and mesh topologies.
Both 802.15.4 and ZigBee have been optimized to ensure that low power consumption is a key feature.
Although nodes with sensors of control mechanisms towards the centre of a network are more likely to have mains power, many towards the extreme may not.
The low power design has enabled battery life to be typically measured in years, enabling the network not to require constant maintenance.
This layer takes care of all network related operations such as network setup, end device connection and disconnection to network, routing, device configurations, etc.
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.
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.