FAQs

FAQs on Zigbee

What is Zigbee? ill effects on each other. In addition, IEEE has defined multiple It is an IEEE 802.15.4 protocol specification intended for digital signal processing methods (e.g. encoding, modulation, close-proximity ad hoc personal area networks hopping, scrambling) and minimum interference rejection (PANs). Conceived in 1998 and standardized in 2003, Zigbee levels to ensure interference rejection and to minimize the has been widely adopted for wireless communication for interference level between different PANs. Finally, there are low-power personal area networks mainly because of several best practices (in terms of channel selection, output its extremely low manufacturing/operation costs and power setting, and placement of access points) that help technological simplicity. As of September of 2017, there minimize the impact of interference. are over 2,200 Zigbee Certified implementations worldwide. What FCC regulations apply to low-power, no-licensed What are the key applications? transmitter such as Zigbee devices? Zigbee is used primarily for remote monitoring, control and Both 2.4GHz and 900MHz are unlicensed industrial, scientific sensor network applications. Examples include wireless light and medical (ISM) radio bands in the US. This means that switches, home energy monitors, traffic management systems, the FCC does not require a license from the Zigbee device and other consumer and industrial equipment that require manufactures to operate in these bands (unlike the AM, FM, or short-range, low-rate wireless data transfer. the cellular spectrum). However, Zigbee device manufactures What are the main advantages of Zigbee? still need to comply with FCC regulation known as Part 15. It is simpler and less expensive to implement than other These low-power transmitters (also found in wireless personal area networks (WPANs), such as Bluetooth, devices) are also referred as “Part 15 transmitters”. And or more general wireless networking such as Wi-Fi. As a manufactures need to obtain FCC authorization before their result, more than 1 billion Zigbee devices have been deployed Zigbee devices can be legally marketed in the United States commercially to-date. What is the coverage area? What is the Zigbee Alliance and its role? The transmission distance is in the range of 10–100 meters The Zigbee Alliance is an open, non-profit industry consortium (line-of-sight); however, longer distance can be achieve created in 2002. Its primary mission is to facilitate and promote through a mesh network of intermediate devices. the development of Zigbee as a universal open standard. Its What is the maximum transmission rate? membership includes over 400 businesses, universities and Data rates vary from 20 kbps (868 MHz band) to 250 kbps government agencies from around the globe. (2.4 GHz band). Star topology Peer-to peer topology What spectrum frequency is used for Zigbee networks? What are the supported Most commercial Zigbee devices operate in the 2.4GHz network topologies? spectrum, although some can use 784 MHz (China), 868 MHz Zigbee networks can be (Europe), and 915MHz (US). built as either a star or a PAN coordinator peer-to-peer network Will Zigbee interfere with other devices (such as (Figure 1). Each of these PAN coordinator WiFi equipment)? Full funcation device networks has a Reduced function device Zigbee (IEEE 802.15.4) and WiFi (IEEE 802.11) networks use the Communication ow designated Full Function same 2.4GHz spectrum and have co-exist for years with little Device (FFD) to work as Figure 1. Zigbee Star and Peer-to-Peer Topology* the coordinator of the network. The peer-to-peer topology In addition, the media access control (MAC) sublayer of the is especially well-suited for the mesh network because it is Zigbee (Figure 3) is responsible for providing self-organizing, self-healing, and can quickly adapt to hooks for implementing application-appropriate security. changes in network topology – effectively avoiding a single Varying levels of data authenticity (to minimize security point of failure. The other benefits are resiliency to indoor overhead), data confidentiality, and replay protection radio propagation effects such as fading and interference, can be supported. since there are always multiple paths in case one network link is not available.

How often does communication happen? Zigbee devices can transmit data synchronously or asynchronously in the network. For a PAN that requires synchronization or support for low-latency devices (e.g. PC peripherals), beacons are used to define a superframe structure (Figure 2). This type of channel access method is also known as the “carrier sense multiple access with collision avoidance” (CSMA-CA). Alternatively, Zigbee devices can utilize the simple communication scheme such as Aloha method for normal data transfers. In this case the Zigbee device would transmit the data whenever there is a frame to send, and the process would repeat until the frame reaches Figure 3. Zigbee protocol stack the destination successfully. How does Zigbee 3.0 relate to the earlier specifications? What does the radio do when the device is idle? All the earlier specifications, standards, or profiles are unified During the inactive period the Zigbee device is able to enter a under the ZigBee 3.0 moniker, which is simply referred to low-power (sleep) mode to preserve energy. as “Zigbee”. Introduced in June 2017, Zigbee Pro is a mesh How secure is Zigbee? networking technology that supports full-stack interoperable The security framework adopted by the Zigbee Alliance is devices certified under Zigbee 3.0. designed to strike the appropriate balance between ease of What is a Zigbee Green Power device? use and secure interaction of devices. Key security features are: Such device uses an open global standard that encompasses • Distributed and centralized network security models energy harvesting capabilities, ultra-lower power RF silicon, • Layered security at the network and application layers network technology, and protocol to • Unique device authentication code (128-bit) protected by a minimize the need for battery change for connected devices. 16-bit cyclic redundancy check CRC error-detection code It is a major technical innovation that removes the power • Runtime key updates during operation obstacles that hinder the potential around the Internet of • Application-layer encryption key between the devices Things as well a major toxic waste stream from • Secure over-the-air (OTA) firmware upgrades the environment. • Additional security features such as frame counting and frequency relocation What is Dotdot? Beacons Introduced by the Zigbee Alliance during the 2017 CES (Consumer Electronic Show), Dotdot is a “common language” designed to ensure interoperability with any other IoT devices Active period at the application layer. This is accomplished by extending the Zigbee Cluster Library (ZCL) to work on devices using a) Superframe without inactive period time the Thread protocol, which uses a radio

Beacons technology similar to Zigbee. For example, through Dotdot other types of IP () networks could also use the ZCL. The first official products could be available as early Active period Inactive period as the end of 2017.

time a) Superframe with inactive period Figure 2. Superframe structure*

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* Figures 1 and 2 were adapted from "IEEE Standard for Local and Metropolitan Area Networks–Part 15.4: Low-Rate Wireless Personal Areas Networks (LR-WPANs)"