Fixed point FFT algorithm realization in OFDM channel estimation

In this paper, four schemes for the fixed point Fast Fourier transform (FFT) algorithm are discussed. Comparisons are made in tradeoff between accuracy and complexity. Several results are obtained through simulation. First, the fixed point schemes given by Welsh and Int-FFT (Integer FFT) scheme by S. Oraintara are compared. Also, the upper bound given by Welsh is tested. Second, based on the comparison, two different methods are chosen for OFDM channel estimation. Our contribution here is that we use two different schemes to perform IFFT and FFT separately. Before being put into implementation, a little change in the fixed-point scheme is made. Last, mean squared errors (MSE) are compared between the float point channel estimation algorithm for OFDM systems and its fixed-point counterpart. The simulation result shows that these two performances are almost the same above 14-bit data quantization. In the paper, accuracy is the main concern and radix-2 is in use.