The Zigbee Alliance released the official IEEE 802.15.4-2003 Zigbee specification in late 2004, which has been revised several times since then and is widely seen as a replacement for Wi-Fi and Bluetooth devices. Zigbee is well suited for low-power devices that require small-scale bandwidth. Zigbee networks support up to 65,000 nodes on a single network. As an open global standard, Zigbee also operates on unlicensed bands at 2.4 GHz, 900 MHz, and 868 MHz. The latest is the Zigbee 3.0 protocol.
Bluetooth Mesh is relatively new. The Bluetooth Special Interest Group (SIG) released the standard in 2017, providing users with the convenience of using local smartphone connections without a gateway, using a flood message relay method based on peer-to-peer. Signals are transmitted directly between nodes. Since there is no centralized node, single points of failure are eliminated. The latest is Mesh 1.1
The maturity of a technology is important for three reasons. First, all new technologies have bugs and issues that take time to work out. Second, documentation becomes more comprehensive over time. The last reason is that compatible hardware takes time to become available.
Zigbee is comparable in maturity to the first two, but hardware compatibility is another story. There are many dedicated Zigbee microcontrollers and SoCs (systems on a chip), but Bluetooth Mesh uses the BLE hardware that is already widely available today. This brings us to the first highlight of Bluetooth Mesh. Both Zigbee and Bluetooth Mesh operate unlicensed in the global 2.4GHz spectrum, but a wide range of devices have BLE capabilities, and therefore Bluetooth Mesh capabilities. This is not the case with Zigbee. This means that a Zigbee mesh network requires a gateway to communicate with most other devices, such as smartphones.
Zigbee and Bluetooth Mesh networks have similar inter-node range limitations—ranging from 10 meters to 100 meters, depending on conditions. But Zigbee can support more nodes in the mesh. Bluetooth Mesh has a theoretical limit of 32,000 nodes, while Zigbee has a theoretical limit of 65,000 nodes.
This means that a Zigbee mesh network can theoretically cover twice the area. But in practice, other practical issues will likely limit the size of the network before you get close to reaching the maximum number of nodes supported by either protocol.
Power consumption is a practical issue that engineers must consider, especially when the nodes are powered by batteries. All Zigbee and Bluetooth Mesh nodes acting as routers must be active to transmit data in the mesh. However, end devices in both protocols can be dormant if they do not need to participate in the mesh. When active, Bluetooth Mesh nodes require less power than Zigbee nodes. A more important limitation is the data rate of each network. Here again, Bluetooth Mesh wins—at least at first glance. It has an over-the-air data rate of 1Mbps. Zigbee has an over-the-air data rate of 250Kbps. But over-the-air data rate alone is misleading because data hops between multiple nodes. The path that data follows through a mesh network determines the efficiency of data transmission.
Even with a single protocol, mesh network architectures vary. Both the physical location of the nodes and the logical structure of the network determine the architecture. The latter is configurable. For example, if the end device needs to sleep, a Zigbee mesh network can utilize multiple router nodes close to the cluster of end device nodes. If power consumption is not a concern, far fewer router nodes are required. Zigbee is best suited for short-range connections, such as smart home environments. It is simple to install and extends battery life through its inherent low-power usage. However, Zigbee's security protocol is not as advanced as Bluetooth mesh's robust multi-layered security measures. Zigbee networks can be incorporated into applications involving home and building automation, wireless sensor networks, data collection, industrial control systems, embedded sensing, and more. Bluetooth mesh networks are primarily used in lighting and home automation applications. As a flooding message network, Bluetooth mesh is reliable, but speed/efficiency can be affected because transmissions must navigate the entire mesh network to successfully deliver the signal.