Research On Satellite-borne AIS Signal Receiving Technology

The monitoring and safety of maritime transportation are getting more and more attention with the rapid development of maritime transportation0Satellite-based automatic identification system(AIS)appeared naturally.The AIS receiver is installed on a satellite platform for the global sea surveillance.But the field of view of satellite covers multiple AIS self-organizing networks.It leads to the collision of AIS signals in different self-organizing networks,which worsens the receiver performance.This paper focuses on the signal reception technology,the reception of the collision signal is discussed emphatically based on the study of the normal signal reception,the main work is shown as following:1)The non-coherent demodulation of non-collision signal is studied.The performance of differential demodulation is studied with 2 bit differential demodulation as the representative,and the reason of the limited performance is analyzed.The VA based on maximum likelihood theory is simulated.The BER performance of the VA has improved significantly than 2 bit differential demodulation.The SOVA for AIS signal is studied,its performance is improved compared with the VA and it's applied to the demodulation of the separation signal.2)A satellite-based AIS collision signal separation algorithm based on compressed sensing is proposed.Correspondiente model is first established.According to the principle of compressed sensing,the sparseness in the dimension of the received signals is used to separate the signals by the OMP,The sparsity and minimum cross-correlation of separation signal are the optimization target,then the PSO is used for the optimal separation solutions.The simulation results show that the proposed algorithm has better performance of collision signal separation and higher error bit performance than Viterbi algorithm.3)An improved FastICA to separate collision signal of satellite-based AIS is proposed,considering FastICA is easily trapped in the local optimum due to the random selection of the initial value of Newton iteration.The improved FastICA uses the cuckoo search to optimize the initial value of the Newton iteration in the way of global search.The performance of satellite-AIS collision signal separation is optimized.Simulation results show that it has less sensitivity to the received signals' power and frequency and it also has good real-time performance compared with FastICA.