BER PERFORMANCE ANALYSIS OF FFT AND DWT OFDM USING DPSK IN THE PRESENCE OF CFO

Orthogonal Frequency Division Multiplexing (OFDM) is a multicarrier modulation scheme which has been adopted in many wireless communication standards . Conventional OFDM uses Inverse Fourier Transform (IFFT) in the transmitter side and Fast Fourier Transform (FFT) in the receiver side. One of the drawback of FFT OFDM is the performance degradation in the presence of Carrier Frequency Offset (CFO). Many research works proven that replacing the Fast Fourier Transform (FFT) by Discrete Wavelet Transform (DWT) shows better performance. IFFT is replaced by Inverse Discrete Wavelet Transform (IDWT) and FFT is replaced by DWT (Discrete Wavelet Transform) in the conventional OFDM. DP SK modulation scheme is used in this work. In this paper both FFT OFDM and DWT OFDM are compared in the presence of Carrier Frequency Offset (CFO) in Additive White Gaussian Noise (AWGN) channel . Bit Error Rate (BER)of both FFT OFDM an d DWT OFDM is compared in the presence of CFO. The result shows that DWT OFDM out performs FFT OFDM.