基于互信息理论的MIMO天波超视距雷达波形优化方法

摘要

Multiple input multiple output (MIMO) sky-wave over-the-horizon radar (OTHR) transmits the wide beams with low gain at the transmitter, and achieves receiver beam-forming to get narrow beams with high gain. The MIMO technique is an ideal choice for OTHR to detect the target through the multi-layer ionosphere and suppress the strong clutters. This paper applies a two-layer ionospheric model in MIMO-OTHR, and proposes a mutual information method to adaptively optimize the waveforms in order to suppress strong clutters with high clutter-to-noise ratio (CNR). Numerical experiments show that this method improves range resolution and detection probability significantly. It also demonstrates that, by applying the optimization method, the multipath propagation can be utilized to enhance the radar performance.%多输入多输出(MIMO)天波超视距雷达(OTHR)技术在雷达发射端发射低增益宽波束，在接收端进行波束形成得到高增益的窄波束，可以满足多层电离层探测和杂波抑制的需求。该文将两层电离层结构应用到MIMO-OTHR中，并针对OTHR杂噪比(CNR)比较高的特点，提出一种互信息理论方法对发射波形进行自适应优化。仿真结果表明该方法明显提升了目标距离分辨率和检测概率，说明在MIMO-OTHR中，经过合理的波形优化，可以利用多径回波改善雷达系统性能。