Let us think of a use case where a large number of battery-operated devices need to be connected. Will Bluetooth or WIFI suffice? Maybe not, because WIFI consumes a lot of power and is therefore not ideal for battery-operated devices. And with Bluetooth, you can connect only a limited number of devices. So, what could be a better solution to join a large number of battery-operated devices?
Here is when Zigbee comes into the picture. Zigbee is a standard that addresses the need for very low-cost implementation of low-power devices with a low data rate for short-range communications. ZigBee is one of the most used standards for the Internet of Things (IoT). It is an open-source standard developed by Zigbee Alliance, an organization created in 2002 that maintains and publishes the Zigbee standards. The Zigbee Alliance was rebranded to Connectivity Standards Alliance (CSA) in 2011. The Zigbee is built on top of the IEEE 802.15.4 physical layer and is designed to meet the needs of low-cost battery-operated applications where extended battery life is of significant concern. Most of the Zigbee devices spend most of their time power saving mode (Sleep mode). Zigbee operates at a low data rate of 20kbps - 250kbps, and this low data rate is the trade-off we need to live with because we are optimizing for a standard power network protocol that can connect many devices.
The range of ZigBee devices can go up to 75 meters, sometimes 100 meters, and for the outdoor, it can go up to 300 meters. It takes around 300 milliseconds for Zigbee devices to connect to the network, and practically a Zigbee network can contain 100s of devices in its network.
The low cost of implementation is the reason for the simplicity of the technology.
Zigbee uses Mesh Topology to establish communication standards between the concerned devices. In this type of topology, there are three types of ZigBee devices – the coordinator, routers, and end devices. ZigBee coordinator is the most capable device; it is the device that starts the network initially, so it is the root of the network, and there is precisely one coordinator device in each network. Network routers act as intermediate nodes between the coordinator and the end devices. They are responsible for routing traffic between different nodes. And the end devices are the most basic of all three and can only send and receive data. There are two advantages to using a mesh network. First, a mesh network increases the system's reliability. Second, because data transmission happens in a mesh network, the short-range of individual Zigbee devices stops being a problem. We can add many Zigbee devices that need to transmit data just to the neighboring node. This way, very large networks can be built based on Zigbee.
Zigbee has extensive uses in home automation, medical data collection, and industrial control systems. In ZigBee home automation, we have a home automation controller with a software application that controls smart devices. The controller is also called a central hub or simply a hub. The gateway is the interface between the ZigBee network and the web. The gateway is connected to the Internet, and it leads the owner to control his smart home devices from virtually anywhere in the world.
Due to its mesh technology with such low power demand, Zigbee is widely acclaimed in the marketplace and is the perfect local area IoT technology.