Out-of-band radiation reduction in OFDM-based cognitive radio systems

Orthogonal frequency division multiplexing (OFDM) suffers from significant out-of-band radiation due to high sidelobes of modulated subcarriers. In a cognitive radio (CR) system this effect results in high interference between secondary and primary users (PUs). Existing methods for reducing this interference have the drawbacks of significant data transmission rate reduction or high complexity. In this paper a simple and adaptive iterative method is proposed that treats on OFDM signal in both time and frequency domains. Simulation results show that when this algorithm is combined with differential modulation, a high value of sidelobe suppression is achieved while the transmission rate reduction is almost insignificant.