Iterative interference mitigation and channel estimation for LDACS1

Within the Future Communications Infrastructure (FCI), the L-band Digital Aeronautical Communications System (LDACS) has been specified as the air-to-ground data link technology. Being one of the two LDACS candidates recommended for further study by the International Civil Aviation Organization (ICAO), LDACS1 is a frequency-division duplex (FDD) broadband system exploiting orthogonal frequency division multiplexing (OFDM). Due to signals from coexisting L-band radio systems, LDACS1 has to work under impulsive interference. In this paper, we study the iterative interference mitigation and channel estimation techniques for LDACS1, based on soft-input soft-output (SISO) demodulation and decoding schemes. We use a simple time-domain blanking nonlinearity to mitigate impulsive noise, which introduces inter-carrier interference (ICI) in frequency domain. To improve the performance, iterative decoding (ID) is carried out between a SISO demodulator and a SISO decoder, based on the Turbo principle. By taking into consideration imperfect channel state information (CSI), we design our iterative receiver with two loops, i.e., the inner loop for ID and the outer loop for interference mitigation and CSI estimation. We analyze the performance of the proposed iterative receiver by using bit-error rate (BER) simulations and extrinsic information transfer (EXIT) charts.