###### Abstract
The fifth-generation mobile communication technology (5G) has provided new solutions of maritime shore-based communication [16; 17], such as the world's first maritime 5G communication project titled \"LTE, Wi-Fi and 5G Massive MIMO Communications in Maritime Propagation Environments (MAMIME)\", which aims to develop the optimized LTE and Wi-Fi systems, and to research the dedicated 5G solutions for the maritime applications [18; 19]. Through exploration and research, it is found that the propagation of wireless signals over the water is different from the terrestrial communications. From the perspective of the wireless propagation environments, the offshore wireless channel characteristics will be affected by the mixed factors of land and water. For the open propagation environment of the deep sea region, the reflection and shadowing of the sea surface will make an impact on the wireless channel. Moreover, the earth curvature should also be considered as an important influencing factor in long-distance wireless communication. Therefore, considering the difference between water communication and terrestrial communication and the perspective of wireless broadband network deployment and optimization, it is necessary to extract typical channel characteristics through actual channel measurement and build a channel model for the research of offshore wireless communication. This paper presents the ship-to-infrastructure and ship-to-ship wireless channel measurements over the offshore water at 5.9 GHz band with a bandwidth of 100 MHz. Additionally, channel measurements description, typical measurement results and channel characteristics are summarized and presented. The contributions of this paper can be summarized as follows:  
* The broadband wireless channel measurements over the offshore water are presented. In the measurements, 5.9 GHz and 100 MHz are employed as the carrier frequency and bandwidth, respectively. The temporary S2I and S2S wireless communication networks are built. * Typical wireless channel characteristics over the offshore water are extracted. Based on the measurement data, the channel characteristics, including power delay profile, delay spread and propagation path loss are analyzed. The impact from water surface on the wireless channel characteristics are presented. * According to the parameter of the measurement campaign and environment, the effective coverage range of the wireless signal and the channel capacity over the offshore water are predicted and the communication performance is evaluated. The remainder of this paper is organized as follows. In Section 2, the S2I and S2S wireless channel measurements over the offshore water are presented. The measurement data pre-processing and the analysis method are provided. The typical wireless channel characteristics over the offshore water, including power delay profile, delay spread, propagation path loss, and the impact from the water surface, are extracted and analyzed in Section 3. Performance evaluation of offshore communications is predicted by the effective coverage and channel capacity calculating in Section 4. Finally, conclusions are drawn in Section 5.