Zigbee is one of the wireless personal area network (WPAN) specifications. It is designed to meet low-power and low data rate applications and is developed under IEEE 802.15.4 standard by The Zigbee Alliance. Typically, Zigbee is used in establishing a smart home for devices from different manufacturers to communicate with each other to enable automation.

Hence, it is also called the smart home protocol. For example, the light system can be linked to the security cameras, and the coffee maker can be linked to the alarm system so that the coffee is ready for you when you wake up.

If we want a network for short-range communication for streaming audio, we opt for Bluetooth. For streaming videos and larger files, we use Wi-Fi. But, we need a network using which we can connect a large number of battery-powered devices. We can't go for Wi-Fi because of its high energy requirements, and we can't choose Bluetooth even though it consumes less power, as only a small number of devices can be connected using Bluetooth.

We need a network that can connect many battery-powered devices, and the main aspect here is low energy/ power consumption. This is the whole purpose of developing Zigbee Technology. Zigbee revolves around control and sensor networks. Hence, it is one of the most common standards and applications for the Internet of Things (IoT).

Zigbee networks use Mesh Topology, which gives a separate link for every device pair in the Network. Even if one link fails, the Network can utilize another alternate path/ link for communication. Hence, it is reliable.

Wi-Fi and Bluetooth networks, on the other hand, use Star topology, where each node/ device is connected to a central node that can be a hub, router, or switch. If the link to a device fails, the device gets disconnected from the Network. If the central node fails, the whole Network will be down.

The catch with these networks is that they offer a low data rate.

The applications of Zigbee are designed in a way that the required data rate is low. For example, one of the biggest companies that use Zigbee technology is Amazon's smart home services.

These networks are also secured with 128-bit AES symmetric encryption keys. A single Zigbee network can support up to 65,000 nodes. Zigbee also uses the same frequency band as the Wifi-2.4GHz Electromagnetic spectrum. The recent developments of Amazon and Google, like Alexa and Google Home, also support Zigbee connections.

Architecture and Working

In a Zigbee network, there will be three types of devices:

1. Zigbee Coordinator
2. End device
3. Zigbee Router

End Devices:

The End device is a battery-powered device that we use. These devices communicate with the Zigbee Coordinator.

Zigbee Routers:

1. A Zigbee router isn't the same as a Wi-Fi router. It can send information to the Coordinator and route data from Zigbee end devices to the Coordinator.
2. The Zigbee router is a mains-powered device, which means it is directly connected to the house's main power. So, there is no concern about its battery life.

Zigbee Coordinator:

1. The Coordinator is also a mains-powered device, and every Zigbee network will have only one Coordinator.
2. It is responsible for starting and maintaining the Network and selecting the network security mode.
3. It receives the information from the end devices and bridges the information to the home network for us to access from our phones or tablets.

• There can be any Zigbee routers in a network but only one Coordinator.
• A Zigbee end device can't route traffic.
• The Zigbee Coordinator can route traffic and is responsible for establishing the Network in the first place.
• Using the Zigbee routers, We can connect the end devices that are otherwise out of range.
• It helps with the mesh capabilities of the Network by providing alternate links if any one link fails during communication.

Advantages (Pros):

1. Zigbee is the best Network for battery-powered devices as it allows them to turn off/ sleep when they aren't used. When needed, the Network quickly wakes them up, thus saving power.
2. Though battery-powered, Zigbee devices can have a good life span due to the Network's power-saving capabilities.
3. Zigbee is an open standard. There are a large variety of devices available from different manufacturers. Hence, Zigbee devices are available at low costs.
4. The Network stays reliable due to its Mesh Topology.
5. Extending a Wi-Fi network is more time-consuming and costly than extending a Zigbee network.

Disadvantages (Cons):

1. If one Coordinator fails, the whole Network goes down.
2. When the Coordinator is replaced, all the Zigbee devices aren't automatically connected to the new Coordinator. Every connection has to be manually established again.
3. The open standard of Zigbee brought compatibility issues. Not every Zigbee device is compatible with every Zigbee network. Even the devices from the same manufacturer as the other devices in a network might need to be compatible with the Network.
4. Zigbee 3.0 forces the manufacturers to follow a specific standard to be certified, but it still needs to be implemented
5. Due to its low bandwidth, Zigbee doesn't support audio and Video applications like Doorbells and CCTV cameras.

Notable users of Zigbee in Smart home:

1. Amazon
2. Ikea
3. Samsung
4. Panasonic
5. Bosch
6. Huawei
7. Philips
8. Nokia
9. Texas Instrumentals
10. Belkin

The name Zigbee:

Isn't the word Zigbee weird for technology? Here is the analogy behind the name. The word Zigbee refers to the waggle dance of honey bees. When a bee finds a source for nectar or pollen, it returns to the comb and dances to let its nest mates know the source's location, distance, and direction. The bee in the name specifies it all. The Zigbee Alliance found the name suitable, intrigued by the silent yet powerful communication through dance.