Leakage Compensation in OFDM Overlay System for VHF Aircraft Radio

Abstract

In order to increase spectral efficiency, an orthogonal frequency-division multiplexing (OFDM) based overlay system should be operated in the very high frequency (VHF) band in addition to the already existing aeronautical voice communication system. The overlay system is designed not to disturb the transmission of the VHF system, whereas the VHF system causes interference in the overlay system. This influence is even amplified by leakage effects which are a systematic problem of the discrete Fourier transform applied for demodulation at the receiver of the OFDM system. In this paper, we analyze the leakage effects occurring in the considered system and propose a compensation scheme mitigating the wideband deterioration of signal-to-interference-and-noise ratio (SINR) induced by leakage. Simulation results show, that with the proposed compensation method the influence of leakage effects can be reduced to the noise floor. Moreover, several simplifications of the compensation algorithm are proposed in order to reduce computational complexity.