Research on Iterative Receiving Algorithm for Aviation Communication System

To cope with the growth of traffic and the need for high-speed transmission, the next-generation aviation communication technology considers deploying the L-bond digital aeronautical communication system (L-DACS1) based on orthogonal frequency division multiplexing (OFDM) in ground-to-air scenarios. But the aviation channel with strong multipath, long-distance, Doppler frequency shift and other characteristics is likely to cause severe channel fading, which affects the reliability of the system and requires channel equalization. At present, the traditional one-time equalization algorithms are generally used in the research of channel equalization in aviation communication systems, but the performance is not ideal. This paper firstly introduces the idea of iteration to the aviation communication system, proposes to use SISO (soft input soft output) equalizer and SISO decoder at the receiving end, and design the iterative receiving algorithm of joint equalization and decoding to realize signal reception. After an in-depth study of linear minimum mean square error (LMMSE) algorithm and Gaussian approximate message passing (AMP-G) algorithm, simulations were built to analyze system performance. The results show that both algorithms can significantly reduce the bit error rate, improve the system reliability, obtain 0.6 dB gain through iteration, save receiver power, and increase the flight radius. The iterative receiving algorithm can improve flight safety, optimize user experience in civil systems, and resist interference, increase the combat range in military systems, so it has broad applications.