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

National Institute Of Science & Technology OFDM Deepak Ranjan Panda (EI ) [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

National Institute Of Science & Technology OFDM Deepak Ranjan Panda (EI ) [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

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

National Institute Of Science & Technology OFDM Deepak Ranjan Panda (EI ) [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

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

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

National Institute Of Science & Technology OFDM Deepak Ranjan Panda (EI ) [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

National Institute Of Science & Technology OFDM Deepak Ranjan Panda (EI ) [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

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

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

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

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

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

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

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