Successive Interference Cancellation for Asynchronous Signal Collision in Space-based AIS

Space-based AIS (Automatic Identification System) is used for global maritime traffic monitoring and safety. In this system, the communication quality deteriorates due to inter-ference by asynchronously colliding AIS signals from multiple ships. In order to suppress this interference and improve the communication quality, this paper proposes a new successive interference cancellation (SIC) scheme for dealing with asyn-chronous signal collisions. The proposed method successively estimates the delays and frequencies in order of signal strength and demodulates them. Then, it generates replicas of the de-modulated signals and subtracts the replicas from the desired signal, enabling it to eliminate the interference caused by signal collisions. In addition, this method generates highly accurate replicas by estimating the phase noise and bandwidth-time (BT) product of each arriving signal which would otherwise reduce the accuracy of the replicas. Moreover, combining SIC with beamforming using multiple antennas can increase the number of signals which can be demodulated. The simulation results show that our proposed method can improve the packet error rate even when the number of interfering waves arriving is more than the number of receiving antennas.