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					4G
 Technology is developing day by diatheses day’s mobile devices are getting more powerful, smaller and
lighter. They have more functions and more capacity as well. With the development of technology, the
battery life also is long and mobiles are also having bigger screen. Further, more we can watch football
games, movies, download music and videos etc through it. Though mobile devices’ technology is
developing the bandwith is always the limiting factor in both wired and wireless devices.

 4G refers to fourth generation technology. It is a successor of 2G and 3G families of standard. 802.20,
WiMAX (802.16), HSDPA, TDD, UMTS are the possible standards for 4G systems. 4G system is aimed to
be based on Orthogonal Frequency Division Multiplexing (OFDM). It is the key of 4G technology.
Adaptive processing and antennas are the other aspects of 4G system. OFDM is specially designed to
send data over hundreds of parallel streams that helps increase the amount of information and also can
be sent all information at a time over CDMA networks. But 3G networks send data digitally over a single
channel. That data rates in 4G depends upon the numbers of channels used.

   The 4G holds the aspects like adaptive processing and antennas to avoid more interference during the
transmission of signals. The adaptive processing detects interference and improves the reception by
switching the channels. This process avoids the interferences. Apart from that, it also uses smart
antenna technology which cancels out more interference during enhancing of the signals. Orthogonal
Frequency Division Multiplexing (OFDM) is such technology that allows transmission of high data rates
over many channels. This technology is chosen method for the European digital radio (DAB) and Digital
TV (DVB-T). Because of its great benefits, it is being thought to for the future broad band applications
like wireless ATM.

 4G HISTORY
  The first radio telephone service was started in the end of 1940. It was specially designed for
car users to the public landline based telephone networks. Then in 1960, Bell systems
introduced Improved Mobile Telephone Service (IMTS) system. It was an improved system with
direct dialing and more bandwiths. The first analog systems were introduced in the late 60s
which were based upon Improved Mobile Telephone System.

 The 1G or first generation was developed in early seventies. It was an analog system. It carried
two main improvements which were the invention of micro processors and the digitization of
control link between mobile phone and the cell site. Advanced Mobile Phone System (AMPS) is
a 1G mobile system. It was first launched by US. And in the end of eighties, 2G systems were
developed. This system digitized the voice signals and the control links. It had much more
capacity. It means to say that many people could use the phones at the same time. It also gave
better quality.
 3G systems were then introduced. It allows faster communications service, fax and internet
data transfer capabilities. 3G aims to provide these services at anytime and anywhere around
the world. IMT-2000 is a global standard for 3G. Japan first launched 3G networks in 2001.

 Now 4G mobile communications are developed with the aim to provide higher data transfer
rate than 3G. It is planned to be up to 100megabits per second on the motion and 1000 gigabits
per second stationary. 4G will be based on OFDM. It will change the way we live. It will have the
reliable connectivity whenever and however we are.



Objectives of 4G
 The objectives of 4G according to 4G working group are as follows;

   o To provide flexible channel bandwith between 5 and 20 MHz
   o To provide users with data rate of 100Mbit/s while client is in motion with respect to
     station and 1Gbit/s while the client is in rest relative to station.
   o Provision of data rate of at least 100 Mbit/s between any two points around the globe.
   o Maximum link spectral efficiency of 15 bit/s/Hz in the downlink and 6.75 bit/s/Hz in the
     uplink.
   o Provision of system spectral efficiency up to 3 bit/s/Hz/cell in the downlink and 2.25
     bit/s/Hz/cell in the uplink for the indoor use
   o Provide seamless connectivity
   o To provide packet switched network

				
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posted:9/29/2010
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