Compensation of the Impact of Interference Mitigation by Pulse Blanking in OFDM Systems

Abstract

When pulsed interference is mitigated by means of pulse blanking, interference is reduced significantly. However, at the same time certain fractions of the useful orthogonal frequency-division multiplexing (OFDM) signal are erased. Consequently, only moderate improvements are achieved with pulse blanking. When representing the pulse blanking operation as multiplication with a rectangular window exhibiting notches at the positions where blanks are inserted, it becomes obvious, that pulse blanking mainly leads to inter-carrier interference (ICI). In this paper, the compensation of the impact of pulse blanking is proposed by reconstructing and subtracting ICI. The required shape of the subcarrier spectra is derived from the pulse blanking window. For an estimation of the transmitted data symbols and the channel coefficients of each subcarrier an iterative receiver structure is proposed. Simulation results at hand of a realistic interference scenario show that with perfect channel estimation and known data symbols the impact of pulse blanking can be reduced to a small loss in signal-to-noise ratio resulting from the energy loss due to erasing a certain fraction of the OFDM signal. With real channel estimation and estimated data symbols, the ideal case with perfect channel estimation and known data symbols is approached by 1.2 dB after only three iterations.