The Zigbee protocol is a low-power, wireless mesh network that was introduced as a standard in the early noughties by the then Zigbee Alliance, now the Connectivity Standard Alliance (CSA). The protocol has had a significant impact in the IoT industry through its steadfast promotion of interoperability, enhancement of security and fostering of innovation.
A brief history of Zigbee
The growing interest in wireless internet communication technologies for short-range, low-power applications demonstrated that existing protocols like Wi-Fi and Bluetooth had some limitations. While effective in certain use cases, they were not necessarily ideal for applications that needed a long battery life and networking over a large area with minimal infrastructure.
In what was regarded as a recognition of this gap, a group of companies formed the Zigbee Alliance in 2002, with the overarching goal to develop a global standard for low-power, low-data-rate wireless networking. Zigbee was picked as a name in reflecting the mesh network capabilities, zigzagging like the flight patterns of bees communicating in a hive.
Zigbee 1.0 was released in 2004 and introduced the core concepts of Zigbee networking: the roles of coordinators, routers and end devices, and the mesh networking. Zigbee PRO in 2007 introduced enhanced security features and greater scalability.
Prior to 2015, the Zigbee protocol was fragmented into multiple profiles tailored for specific applications such as Zigbee Light Link for lighting control and Zigbee Home Automation for smart home devices. In response, the Alliance introduced Zigbee 3.0, consolidating all profiles into one standard meaning all Zigbee devices could be integrated.
The Zigbee Alliance rebranded as the CSA in 2021, in recognition that its mission has extended beyond promoting the Zigbee protocol to the Matter standard.
How does Zigbee work?
The protocol is seen as an alternative to networks using Wi-Fi and Bluetooth, well suited to applications using low-power devices that don’t require a lot of bandwidth. Using a wireless mesh network, three types of devices communicate; the coordinator, routes and end devices. The coordinators responsible for managing the networks; the routers extend its range through relaying data; and the end devices perform specific tasks like sensing.
Data transmission uses a multi-hop communication model. When an end device needs to send data, it communicates with its parent device, which could be the router or the coordinator. If the parent device is not the final destination, it forwards the data to the next device, continuing until the data reaches its intended recipient. This process uses the mesh network’s structure where multiple paths exist between two devices. If one path fails, the network can reroute the data through another path.
In a podcast episode with Phil Beecher, President and CEO of Wi-SUN Alliance, he explained that because of how wireless mesh networks work, they’re well suited to smart city development where thousands of devices are connected and the disruption caused by a power outage can be reduced or mitigated.
“You have multiple street lights that are maybe 10, 20 metres apart. If a street light is trying to communicate to the back haul network and it can’t get the direct connection, it can talk to its neighbour, which is the next three lines along. That works very well as it extends the range of the network and it means you have less interference between devices,” Beecher said.
The Zigbee protocol also uses different mechanisms to ensure efficient and secure data transmission, including the Ad hoc On-Demand Distance Vector (AODV) routing protocol which discovers routes only when necessary.
When a device needs to send data to another device it has not previously communicated with before, for example, it initiates a route discovery process. The source device broadcasts a route request (RREQ) packet which is propagated through the network. Devices that receive this forward the request until it reaches the destination. The intended device responds with a route reply (RREP) packet, establishing the route for data transmission.
Where is Zigbee used?
Practical applications for a Zigbee network could be a smart home, where devices such as smart lights, security sensors and thermostats are interconnected. The coordinator, integrated into a smart home hub, manages this network. Each smart device, acting as a router or end device, communicates its status and receives commands through the hub. If the user adjusts the thermostat through a mobile app, this command travels through the network – hopping from device to device until it reaches the thermostat, which changes the temperature accordingly.
There’s plenty of other editorial on our sister site, Electronic Specifier! Or you can always join in the conversation by commenting below or visiting our LinkedIn page.
