For designing maritime wireless transmission system, the radio propagation over sea surface needs to be known first. One of the distinct characteristics of maritime radio propagation is the impact of ship motions due to the fluctuation of sea waves. This paper establishes a radio propagation model with the integration of the effects of ship motions. Using such an integrated radio propagation model, the maritime radio propagation characteristics are analyzed and discussed under different transmission distances, different carrier frequencies, and different motion types. Index Terms—Radio propagation, Maritime communications, Channel modeling

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Maritime Radio Propagation with the Effects of Ship Motions

Evaluation of multipath signal loss for AIS signals transmitted on the sea surface

Dear editor, Increase in maritime activities with exclusive economic zones leads to an increase in demands for information security in maritime communication networks. In maritime, all ships must install an automatic identification system (AIS) to ensure navigational safety, including eavesdropper ships (ESs). Therefore, the navigation information of the ships is easy for an operator to obtain via the AIS. In the study of [1], the author proposed a new AIS-based ad hoc network model and an AISbased ad hoc routing protocol for ship-to-ship and ship-to-shore data communications. To enhance the secrecy of wireless communications, physical layer security (PLS) uses the characteristics of wireless channels [2]. A relay-aided PLS is suited for maritime networks. In [3], fountain code and relay-aided PLS techniques were found to be suitable for wireless networks. In [4], the PLS in opportunistic relay selection networks over independent and identically distributed Rayleigh fading channels was studied. We propose a location-information-assisted secure transmission scheme in the space-ocean integrated network. The maritime network ensures security by means of routing and the satellite provides maritime broadcast services. However, with the aid of navigation information, we can use routing to avoid eavesdroppers. If interception by an eavesdropper is unavoidable, the proposed scheme can also limit the received information of eavesdroppers by using power optimization, which reduces the amount of the received encoded packets of eavesdroppers. In addition to power optimization, using multiple transmission links, the scheme can also split the raw data into pieces and transmit it. If the eavesdropper is not able to intercept all the transmission links, it cannot receive enough encoded packets to recover the message. Model. In this study, we consider a multi-user maritime communication scenario. If two ships are close enough, then device-to-device (D2D) communications are enabled. Under the proposed scenario, one high-tower base station (HBS), multiple relay ships (RSs), and a satellite (SAT) cooperatively provide the services for maritime user ships. In particular, the SAT provides broadcast services for user ships. However, the eavesdroppers can also receive fountain packets from the SAT. Thus, the network control center (NCC) executes the transmission scheme and manages the control signals. The NCC can obtain the AIS information and decoding situation of the user ship from the AIS control center. According to the transmission scheme, the NCC selects a secure relay link to transmit signals and plans the routing of D2D communication. Afterward, the control signal of the D2D network and the AIS information can also broadcast together via SAT. More details of the system model are referenced in Appendix A. Algorithm development. The transmission scheme can be divided into two phases: the re-

Secure routing and transmission scheme for space-ocean broadband wireless network

An intelligent electromagnetic environment reconstruction method based on super-resolution generative adversarial network

One of the critical problems fishermen face in deep-sea fishing is the lack of low-cost communication mechanisms to the shore. The Offshore Communication Network (OCN) is a network of fishing vessels at sea whose goal is to provide wireless internet over the ocean. The impact of extreme weather conditions on wireless signals, the inability to deploy additional infrastructure, the movements induced by sea waves, the expanded mobility freedom at sea, and the misalignment of directional antenna links are all unique challenges that cause abrupt signal quality fluctuations in OCN. For this reason, it is necessary to integrate near real-time link quality assessment to improve the resilience of communication. This paper examines the characteristics of marine wireless links and the factors impacting communication using data collected through sea-trial experiments involving multiple fishing vessels. The paper proposes a Bayesian framework for forecasting signal strength by employing historical and real-time data. This hybrid learning integrates offline and online probabilistic learning methods to provide intelligence at edge devices. The evaluation of the learning scheme on real datasets and the comparison with baseline methods under different communication contexts show improved predictive accuracy in OCN links.

https://doi.org/10.1109/access.2023.3235387

Link Characterization and Edge-Centric Predictive Modeling in an Ocean Network

Radio wave propagation test is introduced in this paper. It was held in the sea area near Qingdao city, and involved different band including L band, S band, C band and X band. Using the path loss model given in the International Telecommunication Union (ITU) recommendation propagation 1411, we derived the characteristic parameters such as path loss exponent and shadow fading for different frequencies. The statistic propagation model can be used for providing a reference for ship information communication.

Liu Yong-sheng

Papers

Radio wave propagation characteristics measurement and modeling over the sea