18-04-2012, 03:36 PM
ZIGBEE TECHNOLOGY
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INTRODUCTION:
ZigBee is the name of a specification for a suite of high level communication protocols using small, low-power digital radios base on the IEEE 802.15.4-2006 standard for wireless personal area networks (WPANs), such as wireless headphones connecting with cell phones via short-range radio. The technology is intended to be simpler and less expensive than other WPANs, such as Bluetooth. ZigBee is targeted at radio-frequency (RF) applications that require a low data rate, long battery life, and secure networking.
DEVICE TYPES AND HISTORY
There are three different types of ZigBee devices:
• ZigBee coordinator (ZC): The most capable device, the coordinator forms the root of the network tree and might bridge to other networks. There is exactly one ZigBee coordinator in each network since it is the device that started the network originally. It is able to store information about the network, including acting as the Trust Centre & repository for security keys.
ZigBee Topologies
Topology Overview :
A ZigBee network can adopt one of the three topologies: Star, Tree, Mesh. These are illustrated on the left and briefly described below.
Star Topology :
A Star network has a central node, which is linked to all other nodes in the network. All messages travel via the central node.
Tree Topology :
A Tree network has a top node with a branch/leaf structure below. To reach its destination, a message travels up the tree (as far as necessary) and then down the tree.
Application Framework and SAPs
Application Framework
The Application Framework (AF) contains the application objects and facilitates interaction between the applications and the APS layer. An application object interacts with the APS layer through an interface known as a Service Access Point (SAP).
Joining a ZigBee Network
Once the network has been created by the Co-ordinator, other devices (Routers and End Devices) can join the network. Both Routers and the Co-ordinator have the capability to allow other nodes to join the network. The join process is as follows:
APPLICATIONS:
1.Characteristics(Large data speeds and low energy consumption)
2.Maintenance free networks:
3.Energy savings:
4.Business applications
Conclusion
• Low cost (device, installation, maintenance)
• Low power consumption, simply implemented
• Zigbee devices will be more ecological than its predecessors saving megawatts at it full deployment
• High density of nodes per network Zigbee is poised to become the global control/sensor network standard.