Interference Suppression Techniques For OFDM System

As a multi-carrier communication technology, orthogonal frequency division multiplexing (OFDM)technology, by virtue of its efficient spectrum utilization, high-speed data transmission, good resistanceto multipath fading, anti-inter-symbol interference ability and other technical advantages, has been morewidely used in military and civilian wireless system. As one of the key technical issues, the interferencesuppression technology of OFDM system also becomes a hot research problem for this area.With the interference suppression technology of OFDM system as the object of study, this paperfocuses on narrow-band interference (NBI) and wide-band interference (WBI) techniques in order toimprove the ability of interference suppression for OFDM system.The study content is described as below.(1) NBI suppression method for OFDM systemLearning from the technical idea of the Transform Domain Communication System (TDCS)avoiding NBI, this paper chooses the OFDM system having NBI detection and avoidance capability asthe study object and analyzes the performance of this NBI suppression.Meanwhile, this paper analyzes the influence of different threshold on the system performance andsimulates the suppression performance.(2) WBI suppression method for OFDM systemWith the WBI suppression technology of OFDM system as the object of study, this paper focuseson the suppression method for linear frequency modulation (LFM). This method makes use of thedifferences in distribution characteristics of LFM interference and OFDM signal and proposes LFMinterference suppression method based on fractional Fourier transform (FrFT) filtering. At last, thispaper analyzes the suppression performance of the scheme from two aspects of theoretical analysis andsimulation analysis and simulates the impact of filtering bandwidth on the system performance.