XBee ZigBee networks Introduction to ZigBee
XBee/XBee-PRO ZigBee RF Modules User Guide 34
Introduction to ZigBee
ZigBee is an open global standard built on the IEEE 802.15.4 MAC/PHY. ZigBee defines a network layer above the
802.15.4 layers to support advanced mesh routing capabilities. The ZigBee specification is developed by a
growing consortium of companies that make up the ZigBee Alliance. The Alliance is made up of over 300
members, including semiconductor, module, stack, and software developers.
ZigBee stack layers
The ZigBee stack consists of several layers including the PHY, MAC, Network, Application Support Sublayer (APS),
and ZigBee Device Objects (ZDO) layers. Technically, an Application Framework (AF) layer also exists, but will be
grouped with the APS layer in remaining discussions. The ZigBee layers are shown in the figure below.
A description of each layer appears in the following table:
ZigBee Layer Description
PHY Defines the physical operation of the ZigBee device including receive sensitivity, channel rejection, output
power, number of channels, chip modulation, and transmission rate specifications. Most ZigBee
applications operate on the 2.4 GHz ISM band at a 250kb/s data rate. See the IEEE 802.15.4 specification for
details.
MAC Manages RF data transactions between neighboring devices (point to point). The MAC includes services
such as transmission retry and acknowledgment management, and collision avoidance techniques (CSMA-
CA).
Network Adds routing capabilities that allows RF data packets to traverse multiple devices (multiple “hops”) to route
data from source to destination (peer to peer).
APS (AF) Application layer that defines various addressing objects including profiles, clusters, and endpoints.
ZDO Application layer that provides device and service discovery features and advanced network management
capabilities.
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