What is ZigBee or XBEE?

         Zigbee  or Xbee is a communication protocol used for a suite of high-level communication specially built for control and sensor application on IEEE 804.15.4 

.It uses Media access control(MAC) and physical layers to operate different devices at low data rate. 

it is used to set up wireless personal area networks (WPAN) .

It connects one device with other wirelessly. Basically it is used for remote control and sensor applications.

  

Basic Concept of ZigBee or XBEE

       Zigbee or XBEE transmits signals from one station to the next station extend up to about 10-100 meters, although more greater distances can be reached by broadcast data from one node to the next node in a network. 

One Zigbee network can contain more than 65,000 nodes the network they form may take the shape of star or mesh.

It has standard of 802.15.4 which defines the transmission of low data rate through wireless personal area network(WPAN)

The main applications for 802.15.4 are focused at monitoring and control applications where relatively low rate of data transmission is needed.

 It has long battery life which may vary from several months to years which makes it suitable for many embedded applications such as security, lightening control, sensor applications, home automation etc.

Zigbee/XBEE Architecture

      

Zigbee architecture consist of following three major layers such as

• Physical layer,
• Media access control layer
• Network and application support layer.

          Physical layer:

       It modulates the transmitting signal and demodulates the receiving signal. However the modulation techniques also change for different band for 868 and 915MHz band the binary shift keying modulation is used. For 2.40GHz phase shift keying is used.

 

Frequency	Country	Data rate	Channel number
868.3MHz	Europe	20kbps	0
915 MHz	North America	40kbps	0-10
2.405GHz	Worldwide	250kbps	11-16

                          Table: Frequency band for Physical layer

 

         Media Access Layer (MAC):

         The function of MAC is to access the network by CSMA (Carrier sense multiple access) technique to determine when to transmit to avoid the unnecessary clashes and provide the reliable communication.

 

         Network Layer:

        This layer performs all network related tasks such as setup network, disconnection of the network, Network devices configuration, routing etc. Function of this layer are starting a network managing end devices joining or leaving a network, route discovery and neighbor discovery.

 

          Application Support Layer:

 This layer is responsible for the matching of the two devices and start communication between them according to their needs, services and specification.

 

ZigBee/XBEE Transmission:

It has standard of 802.15.4 which defines the transmission of low data rate through wireless personal area network(WPAN).

 Zigbee/XBEE Operating Modes:

       In ZIGBEE/XBEE the data is transferred in two modes BECON mode and NON-BECON mode.

• In non Becon mode coordinator continuously monitor the incoming data of the system because any time any node can ask for communication. So it has to remain in active mode hence more power is consumed but overall power consumption is low because some devices are inactive.
• In Becon mode when there is no communication from any device then co-ordinater enters in to sleep mode. They only operates whenever communication is require which results in longer battery life and lower duty cycles.

 

  Use or Application: 

       The main applications for 802.15.4 are focused at monitoring and control applications where relatively low rate of data transmission is needed.

 It has long battery life which may vary from several months to years which makes it suitable for many embedded applications such as security, lightening control, sensor applications, home automation etc.