基于接收波束成形的自动识别系统的同信道干扰抑制和解调
Received Beamforming Ｂased Interference Suppression and Demodulation for AIS with Co Channel Interference

自动识别系统卫星接收机可接收来自多个同频段蜂窝信号，不可避免地会产生同信 道的信号干扰，抑制此同信道干扰是自动识别系统的最具挑战性问题之一。为了解决此问题 ，提出波达角估计、波束成形加解调的简单串行接收机结构。此结构首先采用多信号分类(M ultiple signal classification, MUSIC)和Capon等算法估计出目标信号和干扰信号的波达 方向角，然后利用最小方差失真响应(Minimum variance distortionless response, MVD R)、匹配滤波（Matched filter, MF）和最小均方误差（Minimum mean square error, MMS E）等波束成形方法将阵列方向对准目标信号入射方向抑制干扰信号，最后采用二比特差分 解调算法检测有用信号。仿真结果表明：本文提出的结构同单接收天线相比，多天线波束成 形显著地抑制了同信道干扰，极大地改善了高斯滤波最小频移键控(Gaussian filtered min imum shift keying, GMSK)信号解调的误比特率性能。
Automatic identification system （AIS） satellite receive r can receive signals from different cells with the same frequency band， and thes e signals form co channel interference (CCI).　Suppressing CCI is one of t h e most challenging issues of the AIS system. A simple serial receiver structure consisting of a direction of arrival(DOA) estimator, a beamformer and a demodulat or is proposed. In this structure, incident angles of all desired and int erference signals estimated by multiple signal classification (MUSIC) and Capon are given. Then minimum variance distortionless response (MVDR), minimum mean square error (MMSE) and matched filter (M F) beamforming algorithms are employed to make the steering vector align with the incident direction of the desired signal to suppress the undesired interference signals. Finally, a two bit differential demodulation algorithm is applied to d etect the useful signal. The simulation results show that the proposed structure, co mpared with the single receiving antenna, significantly suppresses C CI and notably improves the bit error rate (BER) performance of Gaussian filtered minimum shift keying (GMSK) by using mu ltiple antenna beamforming.