First things first, what is ZigBee? It’s essentially a Wireless technology standard (protocol) that was created to enable low-cost, low-power wireless communication between machines and IoT devices. ZigBee was essentially build for Sensors that use the IEEE 802.15.4 Wireless Standard in which ZigBee works on the 2.4GHz, 900 MHz and 868MHz Frequencies.
Second thing you need to know is that today there are three ZigBee types; (ZigBee Pro, ZigBee RF4CE and also Zigbee IP.) If you wish to keep thing simple, today we’re going to focus on ZigBee Pro, which is the one aimed to provide the foundation for IoT to support Low-Cost while at the same time Highly reliable Network communication between these said devices.
ZigBee RF4CE is designed for device to device communication without the requirement of Mesh Networking functionalities.
ZigBee IP is a standard way to optimize Wireless Mesh Networks through IPv6.
Let’s try and simplify it a bit…
One key feature that ZigBee has, is its ability to use Mesh Networking, as mentioned few moments ago. A Mesh Network is a method for devices to talk to each other and report back to the central hub. The Network is defined in three types: Coordinators, Routers and End Devices. Although all nodes can send and receive data, they each play a different role.
Coordinator: It forms the root of the network tree and may bridge to other networks. There can be one ZigBee coordinator in each network since it is the device that started the network. The coordinator stores information about the network.
Router: It passes data from one device to another. End devices can talk to the routers but cannot talk directly to other end devices without the routers.
End Devices: it does not route data from one end device to another (that is the job of the router). End devices can be mobile devices and can also sleep (to preserve battery power). If a device goes to sleep, it cannot in any way send any more data unless it wakes up by an action or command. If the end device moves, it will also inform the network and it will join again using a new parent.
One of the biggest advantages of ZigBee is the battery life especially when compared with WiFi connected devices. Because of this factor, IoT manufacturers developed thousands of consumer devices.
ZigBee has also disadvantages and once of the biggest ones is, the Coordinator. There can only be ONE coordinator, which means that if this device fails/stops working, the entire ZigBee Mesh Network goes down.
If the coordinator is replaced, the Routers and End Devices will not be able to reconnect. You’ll be required to reconnect them all manually.
That being said, ZigBee is an absolute workhorse in the Home Automation world.