Zigbee Terminology
This page contains a list of terms that are commonly used when discussing Zigbee communication.
See our other Zigbee 101 pages and our FAQs to learn more about these concepts.
We also suggest reviewing this page to learn more about RF terminology.
Common Zigbee Terminology
Application Layer (APL)
Highest protocol layer in the Zigbee wireless network. Consists of the APD, ZDO layers and the application framework.
Application Support Sub-Layer (APS)
The application support sublayer provides an interface between the network layer (NWK) and the application layer (APL). Supports two types of services: data and management.
Attributes
An attribute is data that is associated with a cluster end and the server / client ends of a cluster may each possess multiple attributes. These are modified or communicated through commands.
Attribute Reporting
When the value of an attribute changes, the device can notify other devices. Notifications are sent to all devices with a binding to that cluster on the device in question.
Beacons
In our Zigbee network, Routers periodically transmit beacons to confirm their presence to other network nodes.
Binding
Once devices are on a network, they can perform binding. This is where devices create bindings to establish application layer links. For example, an On/Off switch may perform binding to create a binding to an On/Off Light.
Channel
Zigbee uses the same channel set as specified in 802.15.4. In the 2.4 GHz band, these channels are numbered 11 through 26. Channel numbers 0 through 10 are defined by the sub-1 GHz 802.15.4 radios, but Zigbee (at least to date), doesn't run on the sub-1 GHz radios.
Commands
Commands are used to interact with attributes such as reading and writing. Typically after an operation commands the cluster end that received the command will return a corresponding response.
Coordinator
A Zigbee coordinator (ZC) controls the network and is responsible for forming the network. A coordinator is a router with some additional functionality. The Zigbee coordinator functionality includes selecting the channel to form the network on after scanning for the best network and selecting an extended PAN ID. After forming the network, the coordinator acts as a router.
For most applications the Coordinator has additional roles such as being the trust center and network manager. The trust center manages the security settings and authorizations for the network. The network manager monitors and corrects network issues such as PAN ID conflicts or channel changing due to interference.
End Device (ED)
End devices (ZED) are leaf nodes. They communicate only through their parent nodes and, unlike router devices, cannot relay messages
intended for other nodes.
Extended PAN ID (EPID)
8 byte extended PAN ID. Extension to the regular 16-bit PAN ID added to facilitate provisioning and PAN ID conflict detection.
PAN ID
Personal Area Network Identification. Identifies a network and differentiates it from other networks.
Medium Access Control layer (MAC)
Responsible for generating beacons and synchronizing the device to the beacons(in a beacon enabled network). Also provides association and disassociation services.
Mobile End Device
A sleepy end device with enhanced capabilities that enable it to change its physical location and quickly switch to a new parent router. This device type is a Silicon Labs modification to the basic Zigbee sleepy end device to provide added capabilities and management of mobile devices.
Message Integrity Code
AES-128 is used to create a hash of the entire network portion of the message (header and payload), which is appended to the end of the message. This hash is known as the Message Integrity Code (MIC)
Network Dissolve
Term used to describe the action whereby the coordinator on a network issues a leave request to itself thereby dissolving the network. Existing devices on the network will no longer be able to communicate.
Network Layer (NWK)
The NWK layer is responsible for managing the network formation and Routing. Interfaces between the MAC and APL
Network Leave
Term used to describe the action whereby the coordinator on a network issues a leave request to itself thereby dissolving the network. Existing devices on the network will no longer be able to communicate.
Network Manager
The network manager monitors and corrects network issues such as Zigbee Terminology#PAN ID conflicts or Zigbee Terminology#Channel changing due to interference.
Over the Air (OTA)
Mechanism that allows devices to interact and be upgraded via wireless signals rather than a serial connection.
Non-Sleepy End Device
Does not route messages for other devices but they remain powered during operation. These devices are known as Rx-on-when-idle devices. This is a standard Zigbee device type.
Routing
Routing is the process of selecting the path through which the messages will be relayed to its destination device. The coordinator and routers are responsible for discovering and maintaining the routes in the network.
Sleepy End Device
Power down their radio when idle, and thus con-serve resources. However, they must poll their parent node to receive incoming messages and acknowledgements; no data is sent to the sleepy end device until the end device requests it. Sleepy end devices are also sometimes known as rx-off-when- idle devices. This is a standard Zigbee device type.
Trust Centre
Manages security settings and authorizations for the network.
Zigbee Compliant Platform (ZCP)
Platforms need to be Zigbee specification compliant to allow for product interoperability and these hardware/software technology can in turn be certified.
Zigbee Cluster Library (ZCL)
In Zigbee a Cluster is a message or collection of messages pertaining to a given application domain. Cluster Libraries were designed to provide Cluster reusability by abstracting Clusters across several domains and placing them in a library, organized according to the functional domains (e.g., lighting, on/off,HVAC, closures).
Zigbee Device Object (ZDO)
The ZDO (occupies Endpoint 0 of each node) entity defined by the Zigbee Networking Specification for use in network management and information gathering. Responsible for initializing the APS,NWK and Security Service Provider and can be seen as an interface between the application framework and the APS sublayer.
Zigbee Device Profile (ZDP)
Similar to the application profiles defines in the application framework, there is a profile defined for the ZDO known as the ZDP or also known as the device profile. The ZDP contains contains device descriptions and clusters, however the ZDP clusters do not employ attributes. Another difference between the application profile and the ZDP is that the application profile is created for a specific application, whereas the device profile defines capabilities supported by all Zigbee devices.
Common Wireless Network Terminology
Radio
Radio is a technique that enables the communication of signals representing information over the electromagnetic spectrum. In general the process used is as follows.
- A carrier wave is created, via an oscillator, at a given frequency and with a given bandwidth
- Modulation of this wave with the information to be communicated is performed
- Additional coding of the signal in an effort in an attempt to compensate for the uncertain nature of radio communications and technical artifacts associated with electromagnetic waves is done
- The signal is amplified
- The signal is applied to a transmit antenna, and the signal enters the radio channel
Amplifier
Amplifiers are electronic circuits that boost the power (increase the amplitude) of a signal fed to them. While many different types of amplifiers are broadly applied across many electronic applications, two important amplifiers used in wireless include the power amplifier (PA), which is used to boost the signal sent to a transmit antenna, and the low-noise amplifier (LNA), used to boost the typically very weak signal appearing at a receiving antenna.
*RapidConnect devices are power amplified.
Antenna
An Antenna acts as the interface between the radio waves on the electromagnetic spectrum and the rest of the system.Antennas cover a broad range of designs and applications, from simple "whip" antennas to so-called "smart" antennas with active (powered) electronic components.In general, antenna designs are optimized for a specific range of frequencies, with lower frequencies usually requiring physically larger antennas, and are either "omnidirectional", transmitting towards and receiving from all directions simultaneously, or "directional", optimizing both transmission and reception across a limited number of degrees of arc.
*RapidConnect modules come with SMD Chip Antenna or U.FL RF connector options
Band
A range of frequencies utilized for a given transmission. A band is often subdivided by a given frequency range into channels that are statically or dynamically assigned and individually utilized for a given service or application.
Bandwidth
The range and thus amount of spectrum utilized in a given transmission, with the nominal frequency being the centre of this range.
Capacity
The term capacity is often used to describe the ability of a shared channel to carry the maximum information at any given moment in time, as opposed to maximum throughput for any given transmitter. Capacity refers to an upper bound on the ability of any given channel to support simultaneous, distinct, and diverse communications and is usually more important than throughput in the specification, design and operation of most implementations.
Congestion
Congestion is a phenomenon that occurs when the capacity of a channel is oversubscribed. This leads to the need for queuing that delays access to the channel, at least for some traffic. Techniques designed to address congestion include prioritization schemes such as quality of service (QoS) and class of service (CoS); data compression; and the addition of more capacity via the utilization of additional bands or channels.
Interference
Interference is a general term for signals that conflict with a given signal that is intentionally being transmitted. The net effect of interference is a given signal in effect becomes weaker, even to the point where the intended receiver can no longer detect the signal.
Line of Sight (LoS)
Line of sight refers to a clear, unobstructed physical path between a given transmitter and receiver. For many applications, LoS is essential, especially at very high frequencies which only propagate linearly and not very well (if at all) through obstructions. When LoS is not feasible, it may be possible to use additional radios to relay around the obstruction, with the use of mesh techniques. Mesh Network topologies are the backbone of Zigbee networks as well as other IoT standards.
Wireless Network Topology
Topology refers to the logical and/or geometric orientation of a given network implementation. In wireless, three key topologies come into play
- "P2P"(point-to-point) means that every node in a given network must be able to communicate directly with every other node. The logistics here can become quite complex, so P2P is limited to single connections between two nodes or for connections among a small number of nodes within close physical proximity to one another.
- A "Star" (point-to-multipoint) configuration where all traffic between nodes in the network (and beyond, via bridging) must go through a single central point. For instance, Cellular networks are P2MP with handoff of client traffic to other cells via backhaul facilities.
- "Mesh" configuration enables the construction of arbitrarily large and complex configurations by enabling traffic to flow through intermediate nodes, which act like switches forwarding traffic not intended for the relaying node itself. Many possible implementations and configurations are possible here, and both infrastructure and client nodes can, in theory, serve as relay points.
References:
Legal Notices
Copyright © 2020 MMB Networks, Inc. All rights reserved.
Confidential materials prepared and delivered by MMB Networks for receipt and review only by any partner subject to a valid and enforceable MMB Networks confidentiality agreement. Any receipt, review, or misuse of any of the content exchanged hereunder by any party not a party to this confidential exchange shall be subject to any and all rights available under the law. All rights, title and interest to the materials shall remain with MMB Networks.
Any suggestions provided to MMB Networks with respect to MMB Networks' products or services shall be collectively deemed “Feedback.” You, on behalf of yourself, or if you are providing Feedback on behalf of your employer or another entity, represent and warrant that you have full legal authority to bind such entity to these terms, agree to grant and hereby grant to MMB Networks a nonexclusive, perpetual, irrevocable, royalty free, worldwide license to use and otherwise exploit such Feedback within any MMB Networks products and services.