OFDM receivers using oversampling with rational sampling ratios

In this paper, we propose orthogonal frequency division multiplexing (OFDM) receivers using oversampling, where the oversampling ratio is extended from integers to rational numbers. We propose several receiver structures, which reveal the same performance, with the same oversampling ratio. Since the low-pass filters in general OFDM receivers are not ideal, additional noise is introduced into the side bands of the demodulated signal. If we increase the sampling frequency above the symbol rate, subcarriers with higher frequencies than we want are obtained and composed of noise only. Removing the unwanted higher frequency components we can reduce the noise and obtain signal-to-noise power ratio gain compared to the conventional symbol rate receivers. Through computer simulations, we verify the proposed method.