Coexistence research on improved cognitive OFDM signal and primary user signal

Active interference cancellation (AIC) is known to be an effective technique for reducing the out-of-band radiation (OBR) of OFDM spilling over the primary user (PU) protected band. In order to ensure the OBR of OFDM is to be minimized, the AIC models with non-cyclic prefix, adding cyclic prefix were deduced and the performance was compared through simulation, then an improved AIC scheme with both cyclic prefix and adding hanning window is compared for cognitive OFDM systems, obtaining significant improvements in terms of notch depth. Further, this paper carried out a novel research on the coexistence of the OFDM with proposed AIC scheme and the signals of discrete carrier signals in 230 MHz band, and then experimental measurements through SystemVue platform validate its effectiveness, which concludes the performance of improved algorithm. In addition, we can observe the bits error radio of primary user signals, which can demonstrate the coexistence of OFDM signal with improved active interference cancellation algorithm and the discrete carrier signal in 230MHz band.