Zigbee in IOT

Features of ZigBee

Most widely deployed enhancement of IEEE 802.15.4.
The ZigBee protocol is defined by layer 3 and above. It works with the 802.15.4 layers 1 and 2.
The standard uses layer 3 and 4 to define additional communication enhancements.
These enhancements include authentication with valid nodes, encryption for security, and a data routing and forwarding capability that enables mesh networking.
The most popular use of ZigBee is wireless sensor networking using the mesh topology.

Important Components

ZigBee

ZigBee Mesh

In a mesh, any node can communicate with any other node within its range.

If nodes are not in range, messages are relayed through intermediate nodes.

This allows the network deployment over large areas.

Meshes have increased network reliability.

For example, if nodes C and F are down, the message packets from A can still be relayed to G via B and E.

ZigBee mesh networks are self-configuring and self-healing.

Types

ZigBee Coordinator (ZC) :

The Coordinator forms the root of the ZigBee networks tree and might act as a bridge between networks.
There is a single ZigBee Coordinator in each network, which originally initiates the network.
It stores information about the network under it and outside it.
It acts as a Trust Center & repository for security keys.

ZigBee Router (ZR) :

Capable of running applications, as well as relaying information between nodes connected to it.

ZigBee End Device (ZED) :

It contains just enough functionality to talk to the parent node, and it cannot relay data from other devices.
This allows the node to be asleep a significant amount of the time thereby enhancing battery life.
Memory requirements and cost of ZEDs are quite low, as compared to ZR or ZC.

ZigBee Network Layer

The network layer uses Ad Hoc On-Demand Distance Vector (AODV)
To find the final destination, the AODV broadcasts a route request to all its immediate neighbors.
The neighbors relay the same information to their neighbors, eventually spreading the request throughout the network.
Upon discovery of the destination, a low-cost path is calculated and informed to the requesting device via unicast messaging.

Applications