1. National Institute Of Science & Technology OFDM Deepak Ranjan Panda (EI200118175) [1] Orthogonal Frequency Division multiplexing (OFDM) Technical Seminar Presentation By Deepak Ranjan Panda Roll # EI200118175 Under the guidance of Mr. Nalla Srinivasu

2. National Institute Of Science & Technology OFDM Deepak Ranjan Panda (EI200118175) [2] What is OFDM? OFDM is a multicarrier system uses discrete Fourier Transform/ Fast Fourier Transform(DFT/ FFT) Available bandwidth is divided into very many narrow bands

3. National Institute Of Science & Technology OFDM Deepak Ranjan Panda (EI200118175) [3] How to implement OFDM ? Fast fourier transform is primarily used At transmitter end coding is done for error correction Modulated by QAM At receiver end the data is recovered by IFFT

4. National Institute Of Science & Technology OFDM Deepak Ranjan Panda (EI200118175) [4] Why use OFDM

5. National Institute Of Science & Technology OFDM Deepak Ranjan Panda (EI200118175) [5] WIDEBAND OFDM  Variation of OFDM  Spacing between the carriers is large enough  A way by which broadband communication can be established.  Errors in the timing of the digitization can be removed by division of channel’s frequency response

6. National Institute Of Science & Technology OFDM Deepak Ranjan Panda (EI200118175) [6] TASKS FOR THE RECEIVER STRUCTURE Timing synchronization Frequency synchronization Sampling-clock synchronization

7. National Institute Of Science & Technology OFDM Deepak Ranjan Panda (EI200118175) [7] Coded orthogonal frequency division multiplexing A modulation scheme used by Digital Audio Broadcast Multipath

8. National Institute Of Science & Technology OFDM Deepak Ranjan Panda (EI200118175) [8] Wideband & narrowband wireless transmission  The natuer of wireless communication depends on duration of transmission of symbols  The duration from first received path to last received path gives maximum delay

9. National Institute Of Science & Technology OFDM Deepak Ranjan Panda (EI200118175) [9] Error correction coding COFDM uses convolution coding For every one bit input the output is more than one bits No.of output bits depend on code rate being used

10. National Institute Of Science & Technology OFDM Deepak Ranjan Panda (EI200118175) [10] COFDM Transmitter

11. National Institute Of Science & Technology OFDM Deepak Ranjan Panda (EI200118175) [11] OFDM MODULATOR

12. National Institute Of Science & Technology OFDM Deepak Ranjan Panda (EI200118175) [12] FREQUENCY SPECTRA OF SUB-CARRIERS

13. National Institute Of Science & Technology OFDM Deepak Ranjan Panda (EI200118175) [13] COFDM Receiver

14. National Institute Of Science & Technology OFDM Deepak Ranjan Panda (EI200118175) [14] Cyclic Prefix Including a cyclic prefix to the OFDM symbol

15. National Institute Of Science & Technology OFDM Deepak Ranjan Panda (EI200118175) [15] Applications of OFDM The MMDS system Mobile reception Mobile transmission

16. National Institute Of Science & Technology OFDM Deepak Ranjan Panda (EI200118175) [16] CONCLUSION During the development of OFDM system it became obvious that this has great potential than just transmission to a fixed installation