DME pulse interference mitigation method based on joint orthogonal transform and signal interleaving

To mitigate the deleterious influence of distance measurement equipment (DME) interference on orthogonal frequency division multiplexing (OFDM) receiver of broadband aeronautical data link system operating as an inlay system, a new transmission method for OFDM system is proposed based on a joint orthogonal transform and signal interleaving. Firstly, utilizing the characteristic of DME pulse signal, i.e., it exhibits a strongly correlated Gaussian pulse in the frequency domain, together with the orthogonal transformer and signal interleaver at the transmitter, we use the corresponding signal deinterleaver and inverse orthogonal transformer at the receiver to convert the correlated Gaussian pulse into uncorrelated random pulse. Secondly, the uncorrelated random pulse is reconstructed by expectation maximization (EM) iterative algorithm. Finally, the uncorrelated random pulse is eliminated in frequency domain. Simulation results show that the proposed transmission method for OFDM system based on a joint orthogonal transform and signal interleaving can suppress the correlated DME pulse interference effectively and significantly improve the reliability of the OFDM system.