Active Interference Cancellation for Multiple Narrow-Band Primary Signals in Cognitive OFDM

In Cognitive OFDM, out-of-band (OOB) leakage of OFDM signal should be suppressed in order to avoid interference to primary signals. Active interference cancellation (AIC) is a novel OOB leakage suppressing technique. In this paper, AIC method for multiple narrow-band primary signals (NPSs) in cognitive OFDM is discussed. We propose a sub-optimal method of multiple NPSs AIC, which takes different NPSs´ frequency locations and bandwidths into account. Besides, we provide a matrix elements pre-nullifying method to drop computational complexity of the sub-optimal method. Simulation results show that the NPSs´ frequency locations have no significant impact on performance of multiple NPSs AIC method, while the performance is worse with increase of the NPSs´ bandwidths. The low complexity multiple NPSs AIC method reduces complexity greatly, only with slight performance degradation.