HUANG Shilong, ZHENG Xueqiang, CHENG Yunpeng, XU Yuhua, CHEN Juan, ZHOU Xin
With the continuous expansion of China's activities in polar scientific research, resource exploration and development, and polar shipping, the demand for polar communications continues to grow. The shortwave communication, capable of achieving long-distance transmission over thousands of kilometers through ionospheric reflection, features flexible deployment and strong survivability, making it one of the crucial communication means in polar regions. This paper first conducts a detailed analysis of the current research status of the unique ionospheric characteristics in polar regions and ionospheric models. It then reviews the research status of polar shortwave communications across four key areas: shortwave channel modeling, spectrum sensing prediction and channel detection and link establishment, communication waveform design, and ultra-long-distance link design. After that, this study summarizes four major challenges in polar shortwave communications: difficulties in channel modeling, frequency determination, waveform design, and technical verification. Finally, it proposes future research directions of polar shortwave communications from multiple perspectives, including enhanced ionospheric oblique sounding, data-driven frequency prediction, channel detection and communication waveform design, and AI-enabled shortwave communication technologies.