On the out-of-band radiation of DFT-based OFDM using pulse shaping

OFDM is one of the best physical-layer candidates for cognitive radio (CR) systems, but rectangular pulse shaping gives rise to large spectrum sidelobes and interferes with the licensed user on the adjacent band. In this paper, an approach is derived based on the signal continuity to measure the spectral decay rate of the shaping pulse for OFDM. And a novel family of pulses, the power of sech function, is proposed to suppress out-of-band radiation. Several pulse shaping functions are applied to the OFDM system and compared through illustration.