Maritime Wireless Communication Research Articles

Correlation Statistics and Parameter Optimization Algorithms for RIS-Assisted Marine Wireless Communication Systems

Reconfigurable intelligent surfaces (RISs), as one of the potential key technologies in sixth generation (6G) mobile communications, feature low costs, low energy consumption, and ease of deployment. In this paper, we introduce the RIS technology into the maritime wireless communication scenario, which can transform the wireless transmission environment from uncontrollable to controllable. In the considered communication model, we derive the complex channel impulse response for the RIS propagation link and non-line-of-sight propagation link, respectively. This can be used to capture the physical properties of a communication model from different perspectives. Furthermore, based on the designed communication model, we investigate the correlation properties of propagation links in the space and time domains; they are the space correlation statistics and time correlation statistics. The provided framework addresses the technical bottleneck of the existing RIS channel modeling methods that fail to balance precision and efficiency, improves the channel model matching efficiency in the design process of RIS-enabled near-field maritime communication systems, and provides technical support for the rapid development of the 6G mobile communication industry.

Field Measurement and Channel Modeling Around Wailingding Island for Maritime Wireless Communication

Field Measurement and Channel Modeling Around Wailingding Island for Maritime Wireless Communication

An Edge Computing-Based Preventive Framework With Machine Learning- Integration for Anomaly Detection and Risk Management in Maritime Wireless Communications

An Edge Computing-Based Preventive Framework With Machine Learning- Integration for Anomaly Detection and Risk Management in Maritime Wireless Communications

When Maritime Wireless Communications Meet Evaporation Ducts: A Three-Ray Path Loss Modeling Perspective

When Maritime Wireless Communications Meet Evaporation Ducts: A Three-Ray Path Loss Modeling Perspective

Development of a tsunami early warning system on the coast of Palu based on maritime wireless communication

Indonesia, located in the “Ring of Fire” zone, is a tsunami-prone area, especially those earthquake-induced. Therefore, a tsunami early warning system is crucial for reducing potential damage. Ina-TEWS is an Indonesian tsunami early warning system that relies on buoys, uses seismic sensors to detect a tsunami, sends out its warning within 5 min. Ina-TEWS requires maintenance and supervision, especially since 22 buoys were declared lost or damaged in 2012–2018. Therefore, Indonesia needs a faster and more reliable backup early warning system. This study proposes a new method by integrating maritime wireless communication between ships on the open sea and ship-to-coastal radio stations in the Palu Port. The ships used are passenger ships equipped with VHF radio communication which is the main working frequency for signal propagation. Numerical modeling of tsunamis was carried out using Delft3D and Delft Dashboard, using earthquake and fault parameters from PUSGEN. The output of this study is the required VHF signal propagation times for each tsunami scenario less than 1 min. Standard operating procedure (SOP) has also been developed based on the worst scenario. The development of this system is expected to enhance tsunami mitigation systems in Indonesia by replacing the buoys in the future.

Unmanned Surface Vessel Assisted Maritime Wireless Communication Toward 6G: Opportunities and Challenges

Sixth generation (6G) mobile communication aims to construct an autonomous network architecture with human-like consciousness and intelligence. 6G mobile technology is expected to integrate space, air, ground, and sea networks to provide full-dimensional wireless and ubiquitous coverage. Compared to terrestrial communications, maritime wireless communications are still far behind expectations to satisfy 6G requirements for ubiquitous wireless connectivity and extensive coverage. Fortunately, the unmanned surface vessel (USV) with agile maneuverability and adaptive capability is a potential solution to enhance maritime communication coverage and performance. However, how to apply mobile USVs to maritime wireless communication is still an open issue. In this article, we provide an overview of USV-assisted maritime wireless communication by introducing three typical USV application scenarios, basic networking architecture, andvdesign considerations, as well as the main challenges. An example of USV-assisted mobile relaying is conducted to demonstrate the benefits provided by adopting USV in maritime wireless communication.

Tsunami Early Warning System Based on Maritime Wireless Communication

Tsunami buoy, linked to satellite, is commonly used as a tsunami early warning system but has been discovered to have several drawbacks such as the need for approximately 5 minutes to issue an early warning for a tsunami after detecting the initial wave as well as its fragility. It was also reported that the twenty-two buoys placed in the Indonesian seas from 2012 to 2018 were damaged and missing. Therefore, this study proposes a new method for tsunami early warning by integrating ship-to-ship maritime wireless communication. It is important to note that vessels or fishing boats with over 30 GT have the ability to travel more than 100 nmi (approximately 180 km) from the shoreline and can be equipped with point-to-multipoint VHF radio communication. Meanwhile, smaller boats on the fishing ground located approximately 2-5 km from the shore can use a WiFi network to communicate like a wireless mesh while the existing terrestrial network can be used for the ship-to-shore communication between boats and land stations. This system is expected to provide significant benefits for a fishing town such as Pangandaran, West Java, Indonesia which is directly facing Java Megathrust in the Indian Ocean. Therefore, a tsunami numerical simulation was conducted in this study using Shallow Water Equation which involved a hypothetical tsunami simulated from the possible fault source which is approximately 250 km from the source. Moreover, the vessel’s location was assumed to be in line with the fishing ground while the arrival time of the tsunami was estimated from the model to be 22.5 minutes and compared to the relay time of the proposed system which was approximately 5.4 seconds. This is faster in terms of delay than the existing system which relays information through satellite at approximately 5 minutes in an ideal condition and also has the ability to reduce the need for tsunami buoys.

Deep Reinforcement Learning-Based UAV Data Collection and Offloading in NOMA-Enabled Marine IoT Systems

The rapid growth of maritime wireless communication demand and the complex offshore wireless communication environment have brought challenges to ensure the real-time and reliability of data transmission in the marine Internet of Things (MIoT). Unmanned aerial vehicles (UAVs) have great advantages in enhancing coverage and channel quality. Hence, we investigate a UAV-assisted data collection and data offloading system based on nonorthogonal multiple access (NOMA) technology in this paper. We jointly optimize the buoy-UAV association relationship, transmit powers, and the UAV trajectory to minimize the total mission completion time while ensuring data transmission requirements. We first propose a UAV trajectory optimization algorithm based on deep reinforcement learning (DRL). Then, we design a heuristic algorithm to effectively solve the subproblem of power control and the association relationship. Finally, we propose a joint optimization scheme to solve the minimization problem. Simulation results show the effectiveness of the proposed scheme.

Joint Optimization of Trajectory and Communication Resource Allocation for Unmanned Surface Vehicle Enabled Maritime Wireless Networks

In maritime wireless communications, unmanned surface vehicles (USVs) can improve coverage and transmission performance due to their agile maneuverability and flexible deployment. This paper considers a USV-enabled maritime wireless network, where a USV is employed to assist the communication between the terrestrial base station and ships. Considering the maritime environment characteristics and earth curvature, we establish the systematic USV kinetics and information transmission models. To guarantee fairness, we aim to maximize the minimum expected throughput overall ships by jointly optimizing the trajectory and communication resource allocation, subject to the constraints of the USV kinetics, safe sailing, breakpoint distances, line-of-sight links, resource allocation, and information-causality. Due to the complexity of the maritime two-ray signal propagation model, we propose a channel approximation method to find an upper bound of the throughput for the original problem. By the problem decomposition, two sub-problems are derived and solved iteratively using successive convex approximation and interior-point methods. Simulation results confirm the effectiveness of the proposed method and show that USV can significantly improve transmission performance in maritime wireless networks.

Simulation of the effects of evaporation ducts on maritime wireless communication

Simulation of the effects of evaporation ducts on maritime wireless communication

Marine Vision-Based Situational Awareness Using Discriminative Deep Learning: A Survey

The primary task of marine surveillance is to construct a perfect marine situational awareness (MSA) system that serves to safeguard national maritime rights and interests and to maintain blue homeland security. Progress in maritime wireless communication, developments in artificial intelligence, and automation of marine turbines together imply that intelligent shipping is inevitable in future global shipping. Computer vision-based situational awareness provides visual semantic information to human beings that approximates eyesight, which makes it likely to be widely used in the field of intelligent marine transportation. We describe how we combined the visual perception tasks required for marine surveillance with those required for intelligent ship navigation to form a marine computer vision-based situational awareness complex and investigated the key technologies they have in common. Deep learning was a prerequisite activity. We summarize the progress made in four aspects of current research: full scene parsing of an image, target vessel re-identification, target vessel tracking, and multimodal data fusion with data from visual sensors. The paper gives a summary of research to date to provide background for this work and presents brief analyses of existing problems, outlines some state-of-the-art approaches, reviews available mainstream datasets, and indicates the likely direction of future research and development. As far as we know, this paper is the first review of research into the use of deep learning in situational awareness of the ocean surface. It provides a firm foundation for further investigation by researchers in related fields.

Efficient Energy and Delay Tradeoff for Vessel Communications in SDN Based Maritime Wireless Networks

The maritime communication network is assembled by emergent network technologies. However, the adverse maritime environment impedes the efficiency of resources allocation in maritime communication network. Here we show a joint sleeping scheduling and opportunistic transmission scheme in delay-tolerant maritime wireless communication networks based on software defined networking (SDN) to find a better tradeoff between the energy consumption and the delay. Specifically, an energy-limited delay tolerant networking (DTN) node deployed in the ocean receives/transmits data from/to vessels within its communication range. To further save the energy, a long-term energy minimization problem is formulated with sleeping scheduling and opportunistic transmission. After that, a multi-objective minimization problem of energy and delay is first modeled by Lyapunov optimization (LO), which then is solved by convex optimization. Both mathematical analyses and simulation results demonstrate how the maritime communication network allocates satisfactorily with the proposed allocation scheme.

Modulation recognition in maritime multipath channels: A blind equalization-aided deep learning approach

Modulation recognition has been long investigated in the literature, however, the performance could be severely degraded in multipath fading channels especially for high-order Quadrature Amplitude Modulation (QAM) signals. This could be a critical problem in the broadband maritime wireless communications, where various propagation paths with large differences in the time of arrival are very likely to exist. Specifically, multiple paths may stem from the direct path, the reflection paths from the rough sea surface, and the refraction paths from the atmospheric duct, respectively. To address this issue, we propose a novel blind equalization-aided deep learning (DL) approach to recognize QAM signals in the presence of multipath propagation. The proposed approach consists of two modules: A blind equalization module and a subsequent DL network which employs the structure of ResNet. With predefined searching step-sizes for the blind equalization algorithm, which are designed according to the set of modulation formats of interest, the DL network is trained and tested over various multipath channel parameter settings. It is shown that as compared to the conventional DL approaches without equalization, the proposed method can achieve an improvement in the recognition accuracy up to 30% in severe multipath scenarios, especially in the high SNR regime. Moreover, it efficiently reduces the number of training data that is required.

Reconfigurable Sea-Water Based Reflectarray Antenna for UHF Applications

High efficiency sea-water based reflectarray antenna for maritime wireless communications at 740 MHz is introduced in this paper. The proposed reflectarray consists of 169 unit-cell elements with area of 330.2 × 330.2 cm2. Each unit-cell element consists of a cylindrical dielectric container filled with sea-water and is mounted on a conducting plate. It introduces a reflection phase variation from 0 to 313 degrees. The reflectarray is designed and analyzed using the finite integral technique and compared with that calculated using the finite element method. The radiation characteristics of 13 × 13 sea-water based reflectarray are investigated and presented. The main beam direction of the sea-water based reflectarray is controlled by the water level in each unit-cell element through an electronic valves. The reflectarray introduces a maximum gain of 26.2 dB at 740 MHz and 1-dB gain bandwidth of 50 MHz The effect of temperature variation on the electrical properties of sea-water material and their effect on the radiation characteristics of the water-based reflectarray are introduced.

LTE-Maritime: High-Speed Maritime Wireless Communication Based on LTE Technology

The recent advances in wireless communication technologies allow mobile users to access various data services anytime and anywhere on land, while it is one of challenging issues to provide reliable data communications for maritime users due to the geographic features on the sea. Considering the increasing demands of maritime digital data services, we need to develop maritime communications supporting high-speed data rates and extended communication coverage. In this paper, we present the state-of-the-art works related to the data requirements of maritime services and the technical characteristics of existing maritime networks. Then, we introduce a long-term evolution for maritime (LTE-Maritime) that is an ongoing research project in South Korea. The objective of LTE-Maritime is to develop a maritime communication infrastructure supporting the data rates in the order of megabits per second within the communication coverage of 100 km. In order to confirm the feasibility of LTE-Maritime, we implemented a testbed for the LTE-Maritime which consisted of ships equipped with LTE-Maritime routers, base stations (BSs) along the coast, and an operation center. The experimental results show that the LTE-Maritime could be a practical solution for ship-to-shore data communication. Furthermore, we discuss a set of open issues related to the development of LTE-Maritime network.

Multipath Channel Model for Radio Propagation over Sea Surface

When radio signal propagates over the sea, the reflection of sea surface and the scattering of sea waves result in multipath components of the transmitted signal at the receiver. This paper introduces an analytical approach for developing multipath channel model for maritime wireless communications over sea. The presented modeling approach can establish the channel impulse response consisting of specular multipath and diffuse multipath produced by smooth sea surface and rough sea surface, respectively. Specifically, the diffuse multipath is obtained by accumulating diffuse scattering energy from the glistening surface. The methods for deriving specular multipath and diffuse multipath are given in detail. Finally, the numerical results of multipath channel models under different transmission conditions are obtained and analyzed using the introduced channel modeling approach.

High-Performance Time-Code Diversity Scheme for Shore-to-Sea Maritime Visible-Light Communication

This paper presents a novel shore-to-sea maritime data transmission system based on time-code diversity, using visible light in maritime environments to overcome the limitations of conventional maritime wireless communications. The proposed system is primarily comprised of existing LED-based lighthouses and maritime transceivers (marine beacons, buoys, etc.), and thus is considered cost-effective in terms of implementation. We first analyze maritime visible-light communications on the basis of the unique properties of a maritime environment, i.e. sea states (wave height, wind speed, etc.), plus atmospheric turbulence, using the Pierson-Moskowitz (PM) and JONSWAP (JS) spectrum models. It is found that the JS model outperforms the PM model, and that the coverage distance depends on the LED power and sea states. To combat maritime fading conditions that significantly degrade performance and coverage distance, we propose a time-code diversity (TCD) scheme in which the delayed versions of the original data are retransmitted using orthogonal Walsh codes. This TCD scheme is found to be superior, in that it offers three orders of magnitude in terms of BER performance, compared to a conventional (non-TCD) transmission scheme. The proposed scheme is robust and efficient in overcoming the effect of impairments present in maritime environments with a BER of approximately $10^{-5}$ and a data rate of 100 Kbps at a distance of 1 km.

Efficient Scheduling for Video Transmissions in Maritime Wireless Communication Networks

This paper develops a framework for vessel surveillance video uploading via maritime wideband communication networks. A broadband wireless network utilizing a time-division-multiple-access (TDMA)-based media access control protocol is employed to establish a shore-side network infrastructure, and a packet store–carry–forward routing mechanism is adopted to achieve intermittent network connectivity in maritime communications. To provide high-quality videos to the administrative authority, a resource allocation problem is formulated to maximize the throughput priority-based video transmission problem, subject to the intermittent network connections and the time indexes such as the release time and deadline of each video packet. To reduce computational complexity, time-capacity mapping is applied to transform the original resource allocation problem into a two-machine nonpreemptive scheduling problem. Three offline scheduling algorithms are proposed, namely, a time-capacity-mapping-based two-phase (TMTP) algorithm for a single machine, a TMTP algorithm for two machines, and an interval graph-theory-based job relay selection (IGTJRS) algorithm. It is mathematically proved that the IGTJRS algorithm has an approximation ratio (i.e., the ratio of the throughput of an optimal schedule to that of the IGTJRS algorithm) of 2 and time complexity of ${\cal O}(n^{2})$ . Simulations results validate the performance of the proposed algorithms, based on real ship route traces obtained from navigation software BLM-Shipping.

High-Efficiency Sea-Water Monopole Antenna for Maritime Wireless Communications

This paper presents a study of sea-water monopole antenna at very high frequency (VHF) band for maritime wireless communications. The sea-water monopole antenna consists of a feeding probe and a sea-water cylinder held by a clear acrylic tube. The feeding probe is loaded with a disk on the top to improve the excitation of TM mode. A theoretical study of the sea-water monopole antenna based on the three-term theory is presented, which has not appeared in literature. Commercial software packages ANSYS HFSS and FEKO are used to simulate this antenna. Experimental results of a fabricated sea-water monopole antenna with a radius of 50 mm show reasonably good agreement with theoretical predictions. Measurement shows that the proposed sea-water antenna has high radiation efficiency. Meanwhile, due to the transparency and liquidity of sea water, the proposed antenna is almost optically transparent and can be easily reconfigurable. The center frequency of the antenna is tunable by lengthening or shortening the water cylinder, while the bandwidth of the antenna can be adjusted by widening or narrowing the water cylinder.

해양 다중 경로 환경에 알맞은 오버랩 기반 처프 확산 대역 전송 기법

The chirp spread spectrum (CSS) technique that transmits data s ignal by using a chirp signal is often used for maritime wireless communication systems such as sound detection radar systems for submarines. However, maritime multipath environment could reduce the data rate of the CSS system. To tackle the problem, an overlap-based CSS transmission scheme is proposed and analyzed in this paper: Based on the approximated Gaussian Q function, we derive a closed form expression of the bit error rate (BER) of the proposed overlap-based CSS system and investigate the mathematical relationship between the number of overlaps and the intersymbol interference (ISI).