Digital front-end design for ofdm receivers with synchronous if sampling

Orthogonal frequency-division multiplexing (OFDM) is a favored technique in digital broadband wireless communications due to its easiness in combating highly dispersive transmission channels. In an OFDM receiver using traditional superheterodyne radio-frequency (RF) front-end, the analog intermediate- frequency (IF) output signal is sampled and converted to a digital IF signal at an IF sampling rate adhering to the bandpass sampling theorem. Since the existence of carrier and the difference in sampling rate, a digital front-end which incorporates spectral shifting and sampling rate conversion is required to convert the digital IF signal to a complex baseband signal at a baseband sampling rate adequate for succeeding OFDM demodulation. In this paper, we discuss the design of the digital front-end for superheterodyne OFDM receivers when the IF sampling rate is synchronous to the time base of the transmitter.