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Appendix A. Glossary of Terms

This chapter defines a collection of terms that are commonly used when talking about networks in general or ZigBee in particular.

ad-hoc network

This term describes the mutable formation of small wireless networks. The peer-to-peer nature of mesh and cluster tree networks allows for this dynamic attribute by distributing the ability to join the network across the network.

application object

Code that implements the application. Each application object maps to one endpoint.

attribute

This term refers to a piece of data that can be passed between devices. A set of attributes is a cluster.

Bluetooth

Bluetooth is a set of standards that describes a short range (10 meter) frequency-hopping radio link between devices.

BPSK

This acronym stands for Binary Phase-Shift Keying. It is the keying of binary data by phase deviations of the carrier.

cluster

This is a ZigBee term that is defined as a container for attributes or as a command/response association. In the Dynamic C implementation of ZigBee, clusters are a collection of functions related to an endpoint.

cluster ID

This term refers to a unique 16-bit number that identifies a specific cluster within an application profile.

cluster tree

This term describes the physical topology of a network, its geometrical shape. For our purposes, a cluster tree network has as its root the coordinator for the WPAN. All routers that subsequently join the network form their own logical cluster.

coordinator

A ZigBee logical device type. There is one and only one coordinator per ZigBee network. This device has the unique responsibility of creating the WPAN.

CSMA-CA

This acronym stands for Carrier Sense Multiple Access/Collision Avoidance. It is a protocol used by a device that wants transmit on a network. The protocol seeks to avoid collisions by checking to see if the channel is clear before transmitting. If it is not clear, the device waits a radom amount of time and checks again.

device description

A device description is a document in a ZigBee profile. It describes the characteristics of a device that is required in the application area of the profile.

end device

This is a ZigBee term that indicates the device in question has no routing capability. It can only send and receive information for its own use. An end device functions as a leaf node in a cluster tree network. The nodes in a star network are all end devices except for the coordinator. A complete mesh network would not contain any end devices, but in practice a design may call for one or more of them.

endpoint

This is a ZigBee term that refers to an addressable unit on a device. For example, an LED or a digital input could be an endpoint on a Rabbit-based board.

FFD

This is an IEEE term that stands for full-function device. An FFD has routing capabilities, as opposed to an RFD (reduced-function device), which does not.

IEEE

Institute of Electrical and Electronics Engineers.

EUI-64

This acronym stands for Extended Unique Identifier 64 bits. It is an IEEE term used to describe the result of the concatenation of the 24-bit value assigned to an organization by the IEEE Registration Authority and a 40-bit extension assigned by that organization.

IrDA

This term stands for Infrared Data Association. It is a standard for transmitting data via infrared light waves. Look Ma! No cables!

LAN

This term stands for local area network. A LAN covers a relatively small area, though a larger area than a PAN. Corporations and academic institutions typically have their own LANs.

mesh

This term describes the physical topology of a network, its geometrical shape. A mesh network, with its dynamic arrangement of nodes, is ideally suited for the nimble world of wireless communication.

multi-hop

This term describes the ability of a message to be handled by intermediary nodes on its way to its destination node. Both mesh and cluster tree topologies are also known as multi-hop networks.

node

Generally, this term describes any device that is part of a network. For a ZigBee wireless network, the term applies to a device containing a single radio that has joined the network and therefore has a network ID.

O-QPSK

This acronym stands for Offset Quadrature Phase-Shift Keying. It is the keying of data by phase deviations of the carrier.

peer-to-peer

The term peer-to-peer refers to the relationship between two separate devices.

On a physical level it can mean the cables or the radio channel connecting the devices. In the physical sense of the term, peer-to-peer is the opposite of star where all devices in the network connect to one central device.

On a logical level, it means that the entities are equal in that they perform the same routing functions as their neighbor. In the logical sense, peer-to-peer is the opposite of the client/server model.

point-to-multipoint

This term refers to the communication path from a single location to multiple locations. Unlike a star topology which only has nodes one hop away from the coordinator node, in a point-to-multipoint ZigBee topology nodes can be several hops away from the coordinator node.

point-to-point

A circuit connecting two nodes only, creating a communication path from a single location to another single location.

profile

A profile (also known as an application profile) is a description of devices required in an application area and their interfaces.

router

A ZigBee logical device type that can route messages from one node to another.

RF

This term stand for radio frequency. The electromagnetic frequencies from 10 kHz to 300 GHz define the RF range. This is above audio range and below infrared light.

RFD

This is an IEEE term that stands for reduced-function device. An RFD does not have the routing capabilities of an FFD. A ZigBee end device and the IEEE reduced-function device both lack routing functions.

RSSI

Received Signal Strength Indicator.

self-healing network

This term describes the process of recovery in a mesh network. For example, if a node fails, the remaining nodes would find alternate routing paths to accomplish their tasks.

star

This term describes the physical topology of a network, its geometrical shape. For our purposes, a star network has as its root the coordinator for the WPAN. All devices that subsequently join the network can only communicate with the coordinator.

UWB

This terms stands for ultra-wideband. It refers to any radio technology that transmits information spread over a bandwidth larger than 500 MHz.

WPAN

This term stands for wireless personal area network. At bare minimum, it takes two devices operating a short distance from one another and communicating on the same physical channel to constitute a WPAN.

ZDO

This is a specialized application object called the ZigBee Device Object. It is addressed as endpoint 0.