Introductory PPT for OFDM and OFDMA

1. ORTHOGONAL FREQUENCY
DIVISION MULTIPLEXING
(OFDM)
MADE BY
AMEYA VIJAY GOKHALE
14070121505
B.TECH (IT) 2014-18

2. INTRODUCTION
 Based on FDM
 Promising technique for achieving high data rate
transmission in mobile environment
 A form of Multicarrier Modulation
 Single data stream is transmitted over a number of
subcarriers

3. THE CONCEPT
 Data to be transmitted is spread over a large number of
carriers
 Each carrier modulated at a low rate & these Carriers are
orthogonal to each other
 Divides the total available bandwidth in the spectrum into
sub-bands for multiple carriers to transmit in parallel.
 Combines a large number of low data rate carriers to
construct a composite high data rate communication
system

4. THE CONCEPT

5. PRINCIPLE

7. Data Coded in Frequency Domain Transformation to Time Domain Channel Frequency
Time Domain Signal Frequency Domain Signal

8. WHY OFDM (FEATURES)
 Can easily adapt to severe channel conditions
 Robust against narrow-band co-channel interference.
 Robust against inter-symbol interference (ISI) and
fading caused by multipath propagation
 better resistant quality to fading

9. ISSUES
 Sensitive to Frequency Errors
 Inter Carrier Interference between Subcarriers
 Sensitive to Doppler Effect
 High Peak to Average Power Ratio
 Complex than FDM

10. APPLICATIONS
 Digital Audio/Video Broadcasting
 WiMAX
 Wireless ATM transmission systems

11. REFERENCES
 Y.Wu and W. Y. Zou, “Orthogonal frequency division
multiplexing: A multi-carrier modulation scheme,” IEEE
Trans. Consumer Electronics, vol. 41, Aug. 1995.
 Leonard J. Cimini, JR.,“Analysis And Simulation Of A
Digital Mobile Channel Using Orthogonal Frequency
Division Multiplexing”, Ieee Transactions On
Communications, Vol. Com-33, July-1985.