Monday, August 17, 2009

ZigBee(Download PPT,Abstract,Report)


  ZigBee  is  an  open  technology  developed  by  the  SigBee  Alliance  to  overcome  the  limitations  of
BLUETOOTH  and Wi-Fi.    ZigBee  is  an  IEEE  802.15.4  standard  for  data  communications  with
business and consumer devices.  It is designed around low-power consumption allowing batteries to
essentially  last  forever.   BLUETOOTH  as we know was developed  to  replace wires and Wi-Fi  to
achieve higher data transfer rate, as such till now nothing has been developed for sensor networking
and  control  machines  which  require  longer  battery  life  and  continuous  working  without  human
intervention.    ZigBee  devices  allow  batteries  to  last  up  to  years  using  primary  cells  (low  cost)
without any chargers (low cost and easy installation).
The ZigBee  standard provides network,  security, and application support services operating on  top
of the IEEE 802.15.4 Medium Access Control (MAC) and Physical Layer (PHY) wireless standard. 
It employs a suite of technologies to enable scalable, self-organizing, self-healing networks that can
manage  various  data  traffic  patterns.    The  network  layer  supports  various  topologies  such  star, clustered tree topology and self healing mesh topology which is essential in Smartdust
Apart  from  easy  installation  and  easy  implementation ZigBee has  a wide  application  area  such  as
home networking,  industrial networking, Smartdust, many more, having different profiles specified
for  each  field.   The  upcoming  of ZigBee will  revolutionize  the  home  networking  and  rest  of  the
wireless world.


  It  was  in  1896  that  Guglielmo Marconi  invented  the  first  wireless  telegraph.    In  1901  he  sent
telegraphic signals across the Atlantic ocean from Cornwall to St. John’s Newfoundland; a distance
of 1800 miles.   Over  the  last century, advances  in wireless  technologies have  led  to  the  radio,  the television, the mobile telephone, and communication satellites.  All type of information can now be
send to any corner of the world. A wireless  network  is  a  flexible  data  communication  system, which  uses wireless media  such  as radio frequency technology to transmit and receive data over the air, minimizing the need for wired connections.   Wireless  networks  are  used  to  augment  rather  than  replace wired  networks  and  are most commonly used  to provide  last few stages of connectivity between a mobile user and a wired network. 
     Wireless  networks  use  electromagnetic  waves  to  communicate  information  from  one  point  to
another  without  relying  on  any  physical  connection.    Radio waves  are  often  referred  to  as  radio carriers because  they  simply perform  the  function of delivering energy  to a  remote  receiver.     The data being  transmitted  is superimposed on  the radio carrier so  that  it can be accurately extracted at the  receiving  end.   Once data  is  superimposed  (modulated) onto  the  radio carrier,  the  radio  signal occupies more than a single frequency, since the frequency or bit rate of the modulating information adds  to  the  carrier.   Multiple  radio  carriers  can  exist  in  the  same  space  at  the  same  time without interfering with  each  other  if  the  radio waves  are  transmitted  on  different  radio  frequencies.   To extract data, a radio receiver tunes in one radio frequency while rejecting all other frequencies.  The modulated signal thus received is then demodulated and the data is extracted from the signal. Wireless  networks  offer  the  following  productivity,  convenience,  and  cost  advantages  over traditional wired networks:


   There is a plethora of standards under the IEEE 802 LMSC (LAN / MAN  Standard Committee).  Of
these even 802.11 has variety of standards, each with a  letter suffix.   These cover everything from
the wireless standards themselves, to standards for security aspects, quality of service and the like:
802.11a – Wireless network bearer operating in the 5 GHz. ISM band with data rate up to 54 Mbps.
802.11b  – Wireless  network  bearer  operating  in  the  2.4 GHz  ISM  band with  data  rates  up  to  11
802.11e – Quality of service and prioritization
802.11f – Handover 
802.11g – Wireless network bearer operating in 24.GHz ISM band with data rates up to 54 Mbps
802.11h – Power control
802.11i – Authentication and encryption
802.11j – Internetworking
802.11k – Measurement reporting
802.11n – stream multiplexing
802.11s – Mesh networking
Of  these  the  standards  that  are  most  widely    known  are  the  network  bearer  standards,  802.11a,
802.11b, 802.11g.

Network types

     There are two types of network that can be formed: infrastructure networks; and ad-hoc networks.
The  infrastructure application  is aimed at office areas or  to provide a “hotspot”.   It can be installed
instead  of  a  wired  system,  and  can  provide  considerable  cost  savings,  especially  when  used  in
established offices.   A backbone wired network  is  still  required  and  is  connected  to a  server.





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