Advanced Blanking Nonlinearity for Mitigating Impulsive Interference in OFDM Systems

In this paper, we introduce advancements of the conventional blanking nonlinearity for OFDM based systems, in the following referred to as advanced blanking nonlinearity. Blanking is a common measure for mitigating impulsive interference which often occurs in wireless communication systems. Although the blanking nonlinearity removes impulsive interference reliably, it possesses various drawbacks for OFDM based systems. In particular, the choice of the blanking threshold, in order to decide whether a received sample is blanked, is a critical issue. We present an algorithm for determining the optimal blanking threshold so as to maximize the signal-to-noise-and-interference ratio after blanking. Another drawback is that the entire received signal is discarded during a blanking interval despite the fact that only a fraction of the spectrum of the OFDM signal might be affected by interference. We show, how blanking can be limited to sub-carriers which are actually affected by interference. Further, we show how these measures can be combined and how a priori information, obtained in an iterative loop, can be incorporated into the proposed scheme. Simulation results incorporating realistic channel and interference models demonstrate the effectiveness of the proposed scheme