What is ZigBee?

A short-range wireless standard for achieving wideband sensor networks

ZigBee Overview

ZigBee (pronounced "jigu-bi") is a short-range wireless standard suitable for building sensor networks for IoT devices, which require energy saving, compactness, and low cost. Although the data communication distance is short, the transfer speed is slow, and the data transfer capacity is small, it has the advantages of being license-free, low cost, and being power-efficient, it can be battery-powered, and has the fast POWER SUPPLIES start-up time.

ZigBee Alliance

Founded in 2001, the ZigBee Alliance (the ZigBee standardization organization) is currently creating and operating specifications for ZigBee, a communications standard originally formulated for home appliances, for wireless networks built between various wireless sensor nodes.
ZigBee SIG Japan is the main organization in Japan promoting ZigBee. One of the features of ZigBee standardization is the specification of flexible profiles to enhance interoperability. Profiles are common rules that ensure smooth interoperability between applications classified by use. Wireless standards such as Bluetooth also have profiles, but only those specified by the standardization organization are recognized, making their application difficult.

Profile

There are three types of ZigBee profiles that are certified: Public Profile defined by the ZigBee Alliance, Published Profile developed and published by manufacturers, and Private Profile operated independently by manufacturers. For example, the Home Automation Profile is defined as a Public Profile, but if a manufacturer has its own manufacturer-specific profile certified, it can use a newly assigned number as a Private Profile. However, since Private Profiles are developed independently by manufacturers and are not required to be made public, the ZigBee Alliance has established network conformance test specifications for the Private Profile and is verifying coexistence with Public Profile-compliant products.

short range wireless standard

Wireless communication network technologies are classified by distance as shown in the diagram below. If we consider the human being as the center, a wireless PAN (Personal Area Network) is one that covers a range of around 10 to 20 meters to network peripheral devices around that human being. Generally, this refers to short-range wireless communication technologies such as wireless PANs, which have a communication distance of around several tens of meters, and the main technologies in this category include ZigBee, Bluetooth, and wireless LAN.

Comparison of each technology

Types	ZigBee	Bluetooth	Wireless LAN	Electronic tags (passive tags)
standard	IEEE802.15.4	IEEE802.15.1	IEEE802.11b/a/g	ISO ⁄ IEC15693X ISO ⁄ IEC18000
frequency	2.4GHz	2.4GHz	2.4GHz 5GHz	135kHz 13.56MHz 2.45GHz
reach distance	Approximately 10m to 75m	Approximately 10m to 100m	Approximately 100m to 300m	Close contact to several meters
Transmission speed	250kbps	1Mbps	11Mbps 54Mbps	－
Power consumption	60mW or less	120mW or less	About 3W	0
Compact and lightweight	Compact and lightweight	Compact and lightweight	small size	Ultra small
price	Inexpensive	Inexpensive	Inexpensive	Inexpensive
Number of connections	Approximately 65,000 pieces	up to 7 pieces	up to 32 pieces	- Reader connection only

IEEE802.15.4

The basic electrical specifications for ZigBee are standardized as IEEE802.15.4. The ZigBee Alliance defines the specifications for the communication protocol between devices at the logical layer and above. It originally repurposed the technology of HomeRF Lite, which was considered as a communication standard for home appliance networks before ZigBee was established.

Device Type

ZigBee devices are divided into physical devices and logical devices.

Physical Devices

According to the IEEE802.15.4 standard, devices are divided into two types: FFDs (Full-Function Devices) with full functionality, and RFDs (Reduced-Function Devices) with limited functionality for cost reduction purposes. FFDs with router functionality play an important role in ZigBee networks. On the other hand, RFDs without router functionality communicate only with the parent FFD as an endpoint terminal.

Physical Device Type	FFD	RFD
Router Function	○	×
Coordinator	○	×
Router	○	×
endpoint	○	○

Logical Devices

Within a network, there are three roles: ZigBee Coordinator (ZC), ZigBee Router (ZR), and ZigBee Endpoint (ZED). There can only be one coordinator in a network, and it has the function of starting up the network. There can be multiple routers in a network, and they can use their data forwarding function to create a multi-hop network that passes data to nodes one after another. These must be physical devices, FFDs.

Logical Device Type	ZigBee Coordinator	ZigBee Router	ZigBee Endpoint
Network launch	○	×	×
Router Function	○	○	×
Published by Peakon	○	○	×
Scope of Management	All nodes	its own child nodes	Himself

Network Topology

ZigBee has three network types: star, tree, and mesh. One feature that is unique to ZigBee wireless networks is the ability to build a mesh network.
The star topology has a ZigBee coordinator (ZigBee router) at the center, with ZigBee endpoints located around it, resulting in a simple network with communication requiring only one hop. Endpoints that only start up when communication is required can create a power-saving network.
In the tree topology, star-type nodes have a parent-child relationship, and the parent assigns addresses to the children. Because addresses can be generated without duplication based on the tree depth and number of child devices, there is no need to store information about the entire network, making it possible to configure large-scale networks without increasing memory consumption.
In the mesh topology, FFDs with router functionality are placed in all nodes, addresses are assigned using "random numbers," and dynamic communication paths are formed. This allows all nodes to have interconnectivity, enabling wide-area connectivity, and easily securing detour paths in the event of a communication failure. However, this makes it difficult to reduce the power consumption of the nodes, resulting in higher power consumption.