ZigBee has come a long way since the wireless standard was first developed to revolutionise automation in the home. Today, ZigBee is on the cusp of revolutionising many automation technologies including smart metering.
The most recent release of the ZigBee standard is the ZigBee-2007 specification that describes both the ZigBee and ZigBee PRO feature sets. Building upon the ZigBee-2006 definition, the latest standard enhances the previous release while retaining backward compatibility within certain types of network environments.
The ZigBee feature set includes tree addressing, unicast, AODV mesh routing, security, broadcast and group communication, and other features. ZigBee PRO uses stochastic addressing instead of tree addressing but uses the same AODV mesh routing. However, there is an alternative many-to-one routing feature available. The PRO set also has support for enhanced security and allows for limited broadcast addressing. Both feature sets allow for additional support for optional frequency agility and fragmentation.
The major difference between the two standards is in how addressing is carried out. Tree addressing within the ZigBee feature set assigns IP addresses hierarchically, while the stochastic addressing scheme present within ZigBee PRO randomly assigns IP addresses to devices and resolves conflicts by constantly monitoring the network and reacting to traffic.
This addressing difference allows the ZigBee protocol to guarantee unique addressing without any monitoring overhead, but PRO benefits from the scalability it provides when the limits of IP-based communications networks are reached. This can happen in networks consisting of more than five hops or in situations where many mobile end devices are in use. ZigBee PRO is able to address these complex communications networks, but requires more time to deploy because time must be allowed to address conflicts.
Both feature sets utilize ad-hoc on-demand distance vector (AODV) routing, but only the PRO set provides support for the many-to-one source routing function. Many-to-one source routing allows for quick establishment of routing for many devices reporting to a single network device, but at the expense of a larger protocol stack. In situations where there are unsolicited bi-directional and peer-to-peer signals, such as in a smart power grid, the many-to-one feature set is not as effective and may not be appropriate.
ZigBee PRO provides support for limited broadcast group addressing that prevents flooding of an entire network when all members of the group are located within a close proximity. This enhancement is useful in reducing network wide communications overhead traffic in large networks, but at the expense of additional code space. Both standards allow for group addressing.
There are other minor differences between the two feature sets, but the one remaining major difference is the high security support present within ZigBee PRO. The enhanced security allows for encryption keys to be established in peer-to-peer connections and provides additional security where devices connected to the network may not be trusted at the application layer. Once again, the enhanced security comes at the expense of overhead required for the additional code that could be needed by the application.
It is important to understand the differences between the two ZigBee feature sets in order to understand how the devices operate together within the same network in a test environment. If the established network currently functions solely under ZigBee, it is important to note that ZigBee PRO devices will only be able to be added to the network as end devices. In other words, within a ZigBee powered network, ZigBee PRO devices can only communicate through a routing device, but cannot take upon routing functions. Conversely, within ZigBee PRO networks, ZigBee devices also can only be added as end devices.
ZigBee has emerged as a popular choice within smart power grids. As more and more smart meter networks are established around the world, it is important to understand the features that are present within the ZigBee standard that was chosen. During the design phase of a smart meter network, the correct choices must be made in order to ensure the sought-after devices and services can be added at a later time without the additional costs involved in having to reconfigure an entire network in order to take advantage of a particular feature.
ZigBee Alliance
http://www.zigbee.org
The most recent release of the ZigBee standard is the ZigBee-2007 specification that describes both the ZigBee and ZigBee PRO feature sets. Building upon the ZigBee-2006 definition, the latest standard enhances the previous release while retaining backward compatibility within certain types of network environments.
The ZigBee feature set includes tree addressing, unicast, AODV mesh routing, security, broadcast and group communication, and other features. ZigBee PRO uses stochastic addressing instead of tree addressing but uses the same AODV mesh routing. However, there is an alternative many-to-one routing feature available. The PRO set also has support for enhanced security and allows for limited broadcast addressing. Both feature sets allow for additional support for optional frequency agility and fragmentation.
The major difference between the two standards is in how addressing is carried out. Tree addressing within the ZigBee feature set assigns IP addresses hierarchically, while the stochastic addressing scheme present within ZigBee PRO randomly assigns IP addresses to devices and resolves conflicts by constantly monitoring the network and reacting to traffic.
This addressing difference allows the ZigBee protocol to guarantee unique addressing without any monitoring overhead, but PRO benefits from the scalability it provides when the limits of IP-based communications networks are reached. This can happen in networks consisting of more than five hops or in situations where many mobile end devices are in use. ZigBee PRO is able to address these complex communications networks, but requires more time to deploy because time must be allowed to address conflicts.
Both feature sets utilize ad-hoc on-demand distance vector (AODV) routing, but only the PRO set provides support for the many-to-one source routing function. Many-to-one source routing allows for quick establishment of routing for many devices reporting to a single network device, but at the expense of a larger protocol stack. In situations where there are unsolicited bi-directional and peer-to-peer signals, such as in a smart power grid, the many-to-one feature set is not as effective and may not be appropriate.
ZigBee PRO provides support for limited broadcast group addressing that prevents flooding of an entire network when all members of the group are located within a close proximity. This enhancement is useful in reducing network wide communications overhead traffic in large networks, but at the expense of additional code space. Both standards allow for group addressing.
There are other minor differences between the two feature sets, but the one remaining major difference is the high security support present within ZigBee PRO. The enhanced security allows for encryption keys to be established in peer-to-peer connections and provides additional security where devices connected to the network may not be trusted at the application layer. Once again, the enhanced security comes at the expense of overhead required for the additional code that could be needed by the application.
It is important to understand the differences between the two ZigBee feature sets in order to understand how the devices operate together within the same network in a test environment. If the established network currently functions solely under ZigBee, it is important to note that ZigBee PRO devices will only be able to be added to the network as end devices. In other words, within a ZigBee powered network, ZigBee PRO devices can only communicate through a routing device, but cannot take upon routing functions. Conversely, within ZigBee PRO networks, ZigBee devices also can only be added as end devices.
ZigBee has emerged as a popular choice within smart power grids. As more and more smart meter networks are established around the world, it is important to understand the features that are present within the ZigBee standard that was chosen. During the design phase of a smart meter network, the correct choices must be made in order to ensure the sought-after devices and services can be added at a later time without the additional costs involved in having to reconfigure an entire network in order to take advantage of a particular feature.
ZigBee Alliance
http://www.zigbee.org
