COMPARATIVE STUDY OF DIFFERENT TRANSFORMS IN OFDM COMMUNICATION SYSTEM

Abstract

The topic of the project is ‘Comparative Study of Different Transforms in OFDM communication system’. Over the year’s communication systems have evolved with a rapid pace. The need for ultra fast, ultra reliable and service in any scenario has resulted in better communication systems over the years. The current standard of 4G uses OFDM which effectively transforms a wideband frequency selective channel into a band of parallel flat fading channels. This is a multi-carrier scheme which is made possible by the use of DFT and IDFT operation. However, there are problems of Carrier-Frequency Offset and high PAPR in OFDM. Also the DFT and IDFT use complex computations. The problem of high PAPR can be reduced using SC-FDMA. Using MATLAB conventional OFDM systems has been simulated for different digital modulation schemes for AWGN channel and BER has been plotted. Also the SC-FDMA system has been simulated and PAPR has been compared with conventional OFDM. Also both the conventional and SC-FDMA systems have been simulated using DCT and DST and BER and PAPR analysis has been done. These transforms use real coefficients only and thus, can be effectively used instead of DFT as DFT involves complex computations.