The ZigBee spec now includes two feature sets: ZigBee and ZigBee PRO. Both define key aspects of how a mesh network operates but ZigBee PRO's feature set offers improved network scalability, resiliency, security, and ease-of-use, especially for larger, more complex networks.
By Bob Gohn, Ember Corp.
Improved ease-of-use and operation
The ZigBee PRO Feature Set also provides some additional features that simplify the use and deployment of ZigBee applications.
One feature (also available optionally in the base ZigBee Feature Set), is Fragmentation. The IEEE 802.15.4 defines a maximum packet size of 128 bytes, which is optimum for short, efficient control and sensor data messaging. However, there may be times where an application desires to send a larger message.
ZigBee now provides a means for the stack to automatically fragment a larger message into smaller ZigBee packets and reassemble the message at the receiving node, relieving the application of this task.
Commissioning a ZigBee network (like any control network), refers to the task of configuring the individual control or sensor devices with the information they need to perform the desired function. This information may include: what network to join, what ZigBee Feature Set is in use, provision of security keys, and establishing command/control binding relationships (i.e. what lights a given switch turns on or off).
Commissioning typically takes place using a dedicated tool (laptop, PDA, etc.) or through a physical interface on the device (perhaps a simple button).
The updated ZigBee specification provides a new "Commissioning Cluster" that standardizes command sets for usual configuration parameters. ZigBee PRO, with its additional security capabilities, allows this commissioning to be performed in a secure manner.
When to use the ZigBee PRO Feature Set?
The additional capabilities provided by the ZigBee PRO Feature Set are useful in ZigBee networks of any size, but are especially useful in relatively large networks (30-50 nodes or more) that will especially benefit from the new scalability features. The use of security with sleeping devices should also drive the use of ZigBee PRO, as the new security functions allow devices to easily rejoin the network if a network key update is missed during sleep.
Developers should also consider the stack functions required by the relevant standard Application Profile for their design. The newly released Home Automation profile can be used with either the ZigBee or ZigBee PRO feature sets, however most applications will likely desire the scalability offered by ZigBee PRO.
Future Application Profiles may require or strongly desire the use of functions only available in the ZigBee PRO feature set, so developers in other application areas, such as advanced metering or building automation, should be watching these developments.
The ZigBee PRO Feature Set: More of a good thing
The ZigBee PRO Feature Set incorporates the learning of several years of ZigBee success. The improved scalability, resiliency, security, and ease-of-use of the ZigBee PRO Feature Set add to the foundation of a very capable, robust, and stable multi-vendor standard for even the most demanding wireless control networks.
About the author
Bob Gohn has over 20 years experience working in both semiconductor and networking equipment companies. Bob has held a number of marketing and engineering positions at companies including Freescale, C-Port, 3Com, Standard Microsystems Corporation, Raycom Systems, Netways, and Hazeltine.
