PROTOCOL
STACK
Let’s
take a closer look at the layered structure of the
ZigBee protocol stack shown in Figure 2. The lower
layers are imported from the IEEE 802.15.4 wireless
personal area network (WPAN) standard, which was approved
in May 2003. 802.15.4 is a general-purpose WPAN standard
that incorporates the lower levels of communication.
You can download the standard for free from the IEEE
web site listed in the Resources section of this article.
|
(Click
here to enlarge)
|
Figure
2—ZigBee provides network structure, routing,
and security, while the more basic physical and
MAC layers are provided by IEEE 802.15.4. |
Although
designated as a WPAN, ZigBee stretches farther than
your desk, so long as the nodes are spread over a
wide area with adequate density. 802.15.4 consists
only of the physical (PHY) and medium access control
(MAC) layers. ZigBee-specific layers manage routing,
discovery, security, and other network-level functions.
The ZigBee sublayers also present a sophisticated
number of profiles for your application.
