Analysis of the Effects of Orthogonal Transformation Techniques on Channel Equalizers Used in OFDM

In this study, it is proposed to combine fast Walsh Hadamard transform (FWHT) with orthogonal transforms such as discrete cosine transform (DCT) and discrete sine transform (DST) to increase the performance of time domain (TDE) and frequency domain channel equalizers (FDE) used in OFDM systems. In order to test the performance of the proposed FWHT FFT/DCT/DST-OFDM waveforms with TDE and FDE, numerical simulation studies are carried out in the frequency selective Rayleigh fading channel environment. From the obtained numerical results, it is understood that the proposed FWHT FFT/DCT/DST OFDM-TDE systems have approximately 8 dB better bit error rate (BER) performance than FWHT FFT/DCT/DST OFDM-FDE methods.