26-07-2012, 03:58 PM
ZIGBEE WIRELESS SYSTEM
[attachment=29118]
INTRODUCTION
ZigBee is a wireless network protocol specifically designed for low data rate sensors and control networks.
There are a number of applications that can benefit from the ZigBee protocol: building automation networks, home security systems, industrial control networks, remote metering and PC peripherals are some of the many possible applications.
Compared to other wireless protocols, the ZigBee wireless protocol offers low complexity, reduced resource requirements and most importantly, a standard set of specifications.
It also offers three frequency bands of operation along with a number of network configurations and optional security capability.
If you are currently exploring alternatives to your existing control network technologies, such as RS-422, RS-485 or proprietary wireless protocol, the ZigBee protocol could be the solution you need.
This application note is specifically designed to assist you in adopting the ZigBee protocol for your application.
ZigBee is expected to provide low cost and low power connectivity for equipment that needs battery life as long as several months to several years but does not require data transfer rates as high as those enabled by Bluetooth. In addition, ZigBee can be implemented in mesh networks larger than is possible with Bluetooth.
NETWORK CONFIGURATIONS
A ZigBee protocol wireless network may assume many types of configurations. In all network configurations, there are at least two main components:
Coordinator node
End device
The ZigBee protocol coordinator is a special variant of a Full Function Device (FFD) that implements a larger set of ZigBee protocol services. An end device may be an FFD or a Reduced Function Device (RFD).
An RFD is the smallest and simplest ZigBee protocol node. It implements only a minimal set of ZigBee protocol services.
A third and optional component, the ZigBee protocol router, is present in some network configurations.
TRAFFIC TYPES
Beacon Generation
Depending on the parameters of the MLME-START.request primitive, the FFD may either operate in a beaconless mode or may begin beacon transmissions either as the PAN coordinator or as a device on a previously established PAN.
An FFD that is not the PAN coordinator shall begin transmitting beacon frames only when it has successfully associated with a PAN.
This primitive also includes macBeaconOrder and macSuperFrameOrder parameters that determine the duration of the beacon interval and the duration of the active and inactive portions.
The time of the transmission of the most recent beacon shall be recorded in macBeaconTxTime and shall be computed so that its value is taken at the same symbol boundary in each beacon frame, the location of which is implementation specific.
Network and Application Support layer :
The network layer permits growth of network sans high power transmitters. This layer can handle huge numbers of nodes. This level in the ZigBee architecture includes the ZigBee Device Object (ZDO), user-defined application profile(s) and the Application Support (APS) sub-layer.
The APS sub-layer's responsibilities include maintenance of tables that enable matching between two devices and communication among them, and also discovery, the aspect that identifies other devices that operate in the operating space of any device.
The responsibility of determining the nature of the device (Coordinator / FFD or RFD) in the network, commencing and replying to binding requests and ensuring a secure relationship between devices rests with the ZDO (Zigbee Define Object). The user-defined application refers to the end device that conforms to the ZigBee Standard.
[attachment=29118]
INTRODUCTION
ZigBee is a wireless network protocol specifically designed for low data rate sensors and control networks.
There are a number of applications that can benefit from the ZigBee protocol: building automation networks, home security systems, industrial control networks, remote metering and PC peripherals are some of the many possible applications.
Compared to other wireless protocols, the ZigBee wireless protocol offers low complexity, reduced resource requirements and most importantly, a standard set of specifications.
It also offers three frequency bands of operation along with a number of network configurations and optional security capability.
If you are currently exploring alternatives to your existing control network technologies, such as RS-422, RS-485 or proprietary wireless protocol, the ZigBee protocol could be the solution you need.
This application note is specifically designed to assist you in adopting the ZigBee protocol for your application.
ZigBee is expected to provide low cost and low power connectivity for equipment that needs battery life as long as several months to several years but does not require data transfer rates as high as those enabled by Bluetooth. In addition, ZigBee can be implemented in mesh networks larger than is possible with Bluetooth.
NETWORK CONFIGURATIONS
A ZigBee protocol wireless network may assume many types of configurations. In all network configurations, there are at least two main components:
Coordinator node
End device
The ZigBee protocol coordinator is a special variant of a Full Function Device (FFD) that implements a larger set of ZigBee protocol services. An end device may be an FFD or a Reduced Function Device (RFD).
An RFD is the smallest and simplest ZigBee protocol node. It implements only a minimal set of ZigBee protocol services.
A third and optional component, the ZigBee protocol router, is present in some network configurations.
TRAFFIC TYPES
Beacon Generation
Depending on the parameters of the MLME-START.request primitive, the FFD may either operate in a beaconless mode or may begin beacon transmissions either as the PAN coordinator or as a device on a previously established PAN.
An FFD that is not the PAN coordinator shall begin transmitting beacon frames only when it has successfully associated with a PAN.
This primitive also includes macBeaconOrder and macSuperFrameOrder parameters that determine the duration of the beacon interval and the duration of the active and inactive portions.
The time of the transmission of the most recent beacon shall be recorded in macBeaconTxTime and shall be computed so that its value is taken at the same symbol boundary in each beacon frame, the location of which is implementation specific.
Network and Application Support layer :
The network layer permits growth of network sans high power transmitters. This layer can handle huge numbers of nodes. This level in the ZigBee architecture includes the ZigBee Device Object (ZDO), user-defined application profile(s) and the Application Support (APS) sub-layer.
The APS sub-layer's responsibilities include maintenance of tables that enable matching between two devices and communication among them, and also discovery, the aspect that identifies other devices that operate in the operating space of any device.
The responsibility of determining the nature of the device (Coordinator / FFD or RFD) in the network, commencing and replying to binding requests and ensuring a secure relationship between devices rests with the ZDO (Zigbee Define Object). The user-defined application refers to the end device that conforms to the ZigBee Standard.