User's Manual

Table Of Contents
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3.XBeeZigBeeNetworks
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:
Networking Concepts
Device Types
ZigBee defines three different device types: coordinator, router, and end device.
Node Types / Sample of a Basic ZigBee Network Topology
A coordinator has the following characteristics: it
Selects a channel and PAN ID (both 64-bit and 16-bit) to start the network
Can allow routers and end devices to join the network
Can assist in routing data
Cannot sleep--should be mains powered
Can buffer RF data packets for sleeping end device children.
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
250kbps 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.