Hybrid Satellite-Terrestrial Communication Networks for the Maritime Internet of Things: Key Technologies, Opportunities, and Challenges

Abstract: With the rapid development of marine activities, there has been an increasing number of maritime mobile terminals, as well as a growing demand for high-speed and ultra-reliable maritime communications to keep them connected. Traditionally, the maritime Internet of Things (IoT) is enabled by maritime satellites. However, satellites are seriously restricted by their high latency and relatively low data rate. As an alternative, shore & island-based base stations (BSs) can be built to extend the coverage of terrestrial networks using fourth-generation (4G), fifth-generation (5G), and beyond 5G services. Unmanned aerial vehicles can also be exploited to serve as aerial maritime BSs. Despite of all these approaches, there are still open issues for an efficient maritime communication network (MCN). For example, due to the complicated electromagnetic propagation environment, the limited geometrically available BS sites, and rigorous service demands from mission-critical applications, conventional communication and networking theories and methods should be tailored for maritime scenarios. Towards this end, we provide a survey on the demand for maritime communications, the state-of-the-art MCNs, and key technologies for enhancing transmission efficiency, extending network coverage, and provisioning maritime-specific services. Future challenges in developing an environment-aware, service-driven, and integrated satellite-air-ground MCN to be smart enough to utilize external auxiliary information, e.g., sea state and atmosphere conditions, are also discussed.

• The paper surveys hybrid satellite-terrestrial communication networks for maritime IoT, analyzing key technologies, opportunities, and challenges.
• Key technologies enhance efficiency using channel models and resource allocation, and extend coverage via hybrid networks like satellite-terrestrial cooperation.
• Maritime-specific services are provisioned using cross-layer designs and environment-aware models, with future work focusing on predictive models and LEO satellite integration.

Hybrid Satellite-Terrestrial Communication Networks for the Maritime Internet of Things

The paper, "Hybrid Satellite-Terrestrial Communication Networks for the Maritime Internet of Things: Key Technologies, Opportunities, and Challenges," presents a comprehensive survey and analysis of current approaches and future directions in the construction of Maritime Communication Networks (MCNs). As maritime activities proliferate and IoT devices become ubiquitous on the ocean, the necessity for advanced communication systems capable of providing high-speed, reliable connectivity is increasingly crucial. This manuscript explores the integration of satellite-terrestrial networks to meet these demands, detailing enabling technologies, addressing challenges, and outlining future research directions.

Summary of Key Insights

The authors categorize the key technologies supporting state-of-the-art MCNs into three primary objectives: enhancing transmission efficiency, extending network coverage, and provisioning maritime-specific services. Each of these categories demands customized solutions distinct from terrestrial networks due to maritime-specific challenges such as dynamic electromagnetic propagation and limited base station availability.

1. Enhancing Transmission Efficiency: Improving data rate and reliability in maritime environments necessitates understanding unique channel characteristics influenced by sea and atmospheric conditions. Recent efforts include exploring sophisticated channel models and leveraging evaporation ducts to optimize signal propagation, using resource allocation strategies, such as dynamic beamforming and scheduling based on large-scale CSI, to modernize transmission efficiency.
2. Extending Network Coverage: The utilization of hybrid networks, combining terrestrial BS, ship-borne, UAV, and satellite systems, is essential for increasing maritime coverage. This section highlights multi-hop networking, phased-array antennas, and interference mitigation as critical advancements. The integration with spaceborne platforms like high-throughput satellites, employing techniques such as multi-spot beams and satellite-terrestrial cooperation, further illustrates the potential to bridge coverage gaps in open oceans.
3. Provisioning Maritime-Specific Services: Unique maritime services demand tailored communication solutions, from secure navigational communications to high-bandwidth infotainment. Strategies include developing cross-layer designs that optimize resource allocation across network layers while tracking platform dynamics to ensure service reliability and quality over vast and variable maritime regions.

Implications and Future Research Directions

The paper emphasizes the necessity for a systematic approach in developing maritime communication solutions that are environment-aware and service-driven, integrating both satellite and terrestrial networks. This approach promises smart, adaptable MCNs capable of supporting diverse maritime IoT applications with varied bandwidth, latency, and reliability requirements.

Future research should focus on creating comprehensive environmental-aware models that leverage auxiliary data such as sea state and meteorological conditions for predictive network behavior. The development of algorithms that can optimize resource usage dynamically and in real-time, based on varying maritime conditions and distributed network topologies, remains an open challenge. The authors recommend further exploration into large-scale deployment of Low Earth Orbit (LEO) satellites to enhance the existing infrastructure, addressing issues related to coverage, resource allocation, and latency.

Conclusion

The integration of hybrid satellite-terrestrial networks for maritime IoT represents a promising frontier for global connectivity innovation. By tailoring communication solutions to the distinct challenges of maritime environments, the research outlined in this paper provides a pathway to developing robust MCNs that align with both current and future maritime application needs. The insights offered herein contribute valuable knowledge to the evolving field of global communication networks, opening avenues for further research and development in maritime communication solutions.