presented by:
V.SATYA SHARON
S.DIVYA SREE

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4G COMMUNICATIONs
Generations:
First Generation :
 1G refers to the first generation of wireless or mobile communications.
 1G had seen key improvements during the 1970`s.
Second Generation:
 By the end of 1980 digital cellular systems were developed.
 2G cellular telecom networks were commercially launched on the GSM
standard.
Third Generation:
These systems provide faster communication services like fax, net, voice etc.,
Why did 3G fail?
Fourth Generation
• Features
• Advantages
• Comparison over 3G
• OFDM plays a vital role
OFDM :
 It means?
 what is the technique used?
 How it eliminates cross talk?
Simple Block Diagram:
Transmitter:
The whole piece of data to be transmitted which is in serial form to parallel using a DEMUX
Receiver:
Individual streams are sent to MUX , representing the original data
Applications:
 Digital Audio Broadcasting.
 OFDM forms the basis for the global ADSL.
 Wireless LAN.
Advantages:
 High Efficiency.
 Eliminates interference and fading.
 Eliminates narrow band co-channel interference.
 Less sensitive to time synchronization errors.