Interference cancellation scheme for uplink cognitive radio systems

This paper investigates the interference cancellation (IC) scheme for uplink cognitive radio systems, using the spectrum underlay strategy where the primary users (PUs) and the secondary users (SUs) coexist and operate in the same spectrum. Joint MMSE-based parallel interference cancellation (PIC) and Turbo decoding scheme is proposed to reduce the interference to the PUs, as well as to the SUs, in which the minimum mean square estimation (MMSE) filter is only employed in the first iteration, regarded as the "weakest link" of the whole detection process, to improve the quality of the preliminary detections results before they are fed to the Turbo decoder. Simulation results show that the proposed scheme can efficiently eliminate the interference to the PUs, as well as to the SUs.