## 2 Evolution of Maritime Communication Networks
### Five/Sixth-Generation-Enabling Technologies  
To meet the diverse demands of this complex and heterogeneous architecture, several enabling technologies coming from 5G or envisioned for 6G are essential [8]. As listed in Table 4, the ongoing evolution toward 5G/6G networks introduces a wide range of enabling technologies across the domains of communication, computing, and AI-driven control. These technologies aim to address the pressing challenges of MCNs, including intermittent coverage, high mobility, energy constraints, and diverse QoS requirements, by offering intelligent, adaptive, and ultra-reliable communication infrastructures. From a communication perspective, technologies like RIS, Non-Orthogonal Multiple Access (NOMA), massive MIMO, and THz communication aim to improve spectral and energy efficiency, provide reliable non-line-of-sight (NLoS) communication, and support high-density maritime scenarios [8; 11; 34]. These are particularly beneficial in dynamic sea environments with fluctuating link quality and sparse infrastructure. RIS can dynamically control and reflect electromagnetic waves, enabling smart control over the radio environment. In MCNs, RIS-equipped buoys or UAVs can assist in creating or strengthening NLoS paths between ships and base stations, overcoming sea clutter and sparse infrastructure issues [35; 36; 37]. NOMA enhances spectrum efficiency by allowing multiple users to share the same frequency band with power-domain multiplexing. In dense port environments or UAV-aided clusters, NOMA enables simultaneous communication among ships or between \begin{table}
\begin{tabular}{c c c} \hline
**Domain** & **Enabling Technology** & **Benefit to MCNs** \\ \hline \multirow{8}{*}{Communication} & RIS Communications & Enhances NLoS links via UAVs or buoys, \\  & useful in harsh sea propagation conditions. \\ \cline{2-3}  & NOMA Communications & Increases spectral efficiency \\  & & for dense S2S/S2 Sh sensor deployments. \\ \cline{2-3}  & THz Communications & Enables ultra-high speed \\  & & short-range links (e.g., UAV-to-ship). \\ \cline{2-3}  & Full-Duplex (FD) & Improves bandwidth efficiency \\  & & in ship relays and sea BS. \\ \cline{2-3}  & Massive MIMO & Enhances directional communication with \\  & & beamforming from shore to moving vessels. \\ \hline \multirow{8}{*}{Computation and Edge Intelligence} & MEC & Real-time processing on ships, UAVs, sea BS \\  & & to reduce latency and satellite load. \\ \cline{2-3}  & Task Offloading & Offload compute-heavy tasks (e.g., analytics) \\ \cline{2-3}  & Task Offloading & from vessels to aerial/satellite nodes. \\ \cline{2-3}  & Digital Twins & Create predictive models for ship operations \\ \cline{2-3}  & & and sea conditions using real-time data. \\ \cline{2-3}  & Federated Learning (FL) & Enables decentralized AI among ships \\  & & and nodes without sharing raw data. \\ \hline \multirow{8}{*}{AI-Driven Networking} & Reinforcement Learning (RL) & Optimal routing, power control, and \\  & scheduling in dynamic maritime topology. \\ \cline{2-3}  & AI-based Resource Allocation & Bandwidth and spectrum optimization \\ \cline{2-3}  & & across links and platforms. \\ \cline{2-3}  & AI-based Spectrum Sensing & Detects interference, adapts to regulatory \\ \cline{2-3}  & & constraints in shared bands. \\ \cline{2-3}  & AI-based Energy Management & Extends UAV and AUV operation \\ \cline{1-1}  & through adaptive control strategies. \\ \hline \end{tabular}
\end{table} 
Table 4: Potential domain-specific 5G/6G enabling technologies and their benefits to MCNs. UAVs and maritime sensors. Also, THz bands provide ultra-high data rates and low latency over short distances. These are promising for near-field, high-bandwidth communication in scenarios such as ship-to-drone data transfer or intra-port logistics coordination. Integrated Sensing and Communication (ISAC) enables joint radar-like sensing and communication functions.