Noncoherent Detection of Satellite-Based AIS Signal with Phase Offset Compensation

Abstract: Considering the existence of large Doppler frequency shift, fast time-varying channels and multiple user interference and other serious problems in the satellite-based AIS system, a noncoherent detection method called phase adaptive algorithm is proposed. For AIS signals, utilizing the characteristic of the energy distribution under the Laurent decomposition of PAM waveform, matched filter is evaluated without whitening filter on the main component. This can effectively avoid the influence of the correlation length on the performance of detection. And the complexity of the system is significantly reduced. The cost function of decoding is given based on maximum likelihood criterion in the algorithm. Multiple symbols as the observation window are decoded at the same time. Meanwhile, phase adaptive compensation is employed in the decoding process. Simulation results show that this method has good detection performance. The BER is close to the ideal coherent detection when the size of observation window is 10 symbols, and is superior to the traditional differential decoding. At the same time, the algorithm has a higher robust and is also applicable to the conditions of multiple user co-channel interference. Copyright © 2014 IFSA Publishing, S. L