Active interference restriction in OFDM-based cognitive radio network using genetic algorithm

In OFDM based cognitive radio networks, minimizing the interference caused to the primary user (PU) by the leakage emission of secondary users (SUs) is a great challenge. In this paper, we propose an interference restriction scheme using the additive signal side-lobe reduction technique and genetic algorithm (GA) in CR-OFDM systems. Additive signal side-lobe reduction technique is based on adding a complex array to modulated data symbols in the constellation plane for sidelobe reduction in OFDM system. In the proposed method, GA generates optimum additive signal which can effectively reduce the SU out-of-band (OOB) signal interference and consequently strives to keep the interference below a tolerable limit pre-defined by PU. The results show that the side-lobes of the OFDM-based SU signal can be reduced by up to 35dB and the PU interference tolerable limit can be satisfied.