Research On Iterative Detection And Receiving Algorithm For Aviation Communication System

In response to the requirement of traffic growth and high-speed transmission,the next generation of aeronautical communication technology considers to deploy L-band Digital Aeronautical Communication system(L-DACS1)based on Orthogonal Frequency Division Multiplexing(OFDM)technology in ground-to-air communication scenarios.But the characteristics of aeronautical channel such as rich multipath,long distance,and Doppler frequency shift can easily cause severe channel fading and affect system reliability.In order to ensure the reliability of aeronautical communications,this thesis considers the methods of iterative detection at the receiving end.The main contributions of the thesis are as follows:1.Aiming at the channel fading problem of L-DACS1 system,iterative detection technology is introduced at the receiving end.By deploying LDPC codes and massive MIMO technologies,three factor graph model-based iterative detection algorithms,i.e.,Turbo LMMSE,AMP-G and AMP-EP are realized.And these iterative detection algorithms are compared with the traditional linear detection algorithm.The simulation results show that the iterative detection receiving algorithms have lower bit error rate,And the iteration convergence times and algorithm complexity are lower.While improving the reliability and safety of the system,it can also reduce the receiver power and improve the flight radius.The iterative detection receiving algorithms are more suitable for the next generation of aviation communication system.2.Aiming at the unknown channel condition of L-DACS1 system,an iterative algorithm combining signal detection and channel estimation is proposed.And it is compared with traditional channel estimation algorithms through simulation.The simulation results show that the iterative channel estimation algorithm has higher channel estimation accuracy and lower complexity than the traditional channel estimation algorithm,and is more suitable for the next generation of aviation communication system.3.Aiming at the problem of colored noise that often exists in actual aviation communication systems,an iterative receiving scheme based on noise whitening is proposed.The simulation results show that the bit error rate of the system superimposed with colored Gaussian noise is significantly deteriorated.And the iterative reception scheme based on noise whitening can solve this problem and ensure the normal communication of the system.