Abstract
The proliferation of wireless devices requires flexible network infrastructures to meet the increasing Quality of Service (QoS) requirements. Mobile Robotic Platforms (MRPs) acting as mobile communications cells are a promising solution to provide on-demand wireless connectivity in dynamic networking scenarios. However, the energy consumption of MRPs is a challenge that must be considered to maximize the availability of the wireless networks created. The main contribution of this paper is the experimental evaluation of the energy consumption of an MRP acting as a mobile communications cell. The evaluation considers different actions performed by a real MRP, demonstrating that energy consumption varies significantly with the type of action performed. The results obtained pave the way for optimizing MRP movement in dynamic networking scenarios, maximizing wireless network's availability while minimizing the MRP energy consumption.

Abstract

Abstract
The growing demands of the Blue Economy are increasingly supported by sensing platforms, including as Autonomous Surface Vehicles (ASVs) and Autonomous Underwater Vehicles (AUVs). Multimodal Underwater Wireless Networks (MUWNs), which may combine acoustic, radio-frequency, and optical wireless technologies, enhance underwater data transmission capabilities. Although Delay-Tolerant Networks (DTNs) address connectivity intermittency in such environments, not all data streams are delay-tolerant, and transmitting high-bandwidth DTN traffic over narrowband links can lead to significant inefficiencies. This paper presents QoS-MUWCom, a Quality of Service (QoS)-aware communication solution designed to manage both real-time and delay-tolerant traffic across dynamically selected multimodal interfaces. Experimental evaluations conducted in a freshwater tank demonstrate that QoS-MUWCom achieves near-zero packet loss for low-demand traffic even under link saturation, improves throughput for prioritized flows up to three times in mobility scenarios, and adapts to link availability and node mobility. The results confirm that QoS-MUWCom outperforms conventional multimodal strategies, contributing to more robust, resilient and efficient underwater communications.

Abstract
Underwater wireless communications face significant challenges due to propagation constraints, limiting the effectiveness of traditional radio and optical technologies. Long-range acoustic communications support distances up to a few kilometers, but suffer from low bandwidth, high error ratios, and multipath interference. Semantic communications, which focus on transmitting extracted semantic features rather than raw data, present a promising solution by significantly reducing the volume of data transmitted over the wireless link. This paper evaluates the resilience of SAGE, a semantic-oriented communications framework that combines semantic processing with Generative Artificial Intelligence (GenAI) to compress and transmit image data as textual descriptions over acoustic links. To assess robustness, we use a custom-tailored simulator that introduces character errors observed in underwater acoustic channels. Evaluation results show that SAGE can successfully reconstruct meaningful image content even under varying error conditions, highlighting its potential for robust and efficient underwater wireless communication in harsh environments.

Abstract
In the coming years, a wide range of underwater applications, including resource mining, marine research, and military operations will play an increasingly important role. The Internet of Underwater Things (IoUT) extends IoT principles to underwater environments, enabling connectivity between underwater devices and the Internet. However, high latency, intermittent connectivity, and security risks, such as privacy breaches, data tampering, and unauthorized access, pose major challenges to IoUT adoption. Existing security mechanisms fail in Delay-Tolerant Networks (DTNs) due to their reliance on centralized trust models. Blockchain provides a decentralized, immutable, and transparent solution for securing underwater communications. This paper introduces the Blockchain-Based Underwater Messaging System (BUMS), an innovative solution that ensures message integrity, confidentiality, and resilience in DTNs. Messages are immutably stored in blockchain blocks, while malicious nodes are autonomously detected and excluded without the need for a central authority. To evaluate its feasibility, we developed the Underwater Blockchain Simulator (UBS), a custom-tailored open-source simulator designed to test blockchain algorithms in underwater networks. Simulation results demonstrate that BUMS enhances security and network reliability while maintaining efficiency in high-latency underwater environments, making it a viable solution for secure IoUT-based communications.

Abstract
Conventional power distribution networks (PDNs), in which individual voltage regulators power the entire integrated circuit (IC), are ineffective for high-power, large-area ICs. In highperformance systems-on-chip (SoCs) and microprocessors (in particular those designed for AI applications), shrinking technology nodes are leading to higher current densities, which impose thermal constraints and limit the portion of the chip that can be simultaneously powered (“dark silicon”). PDNs with point-of-load regulation offer a promising alternative. The distributed nature of their design inherently relaxes thermal constraints while minimizing high-current routing overhead (IR drops), thereby improving the PDN efficiency. In this work, the concept of on-chip distributed voltage regulation is introduced. Previously reported distributed voltage regulator designs are reviewed, emphasizing their major achievements and limitations. Then, the challenges that hinder a more ubiquitous adoption of such designs, namely stability (analysis) and unbalanced load sharing, are discussed. Existing solutions addressing these challenges are also presented. Finally, a comparative analysis of the performance of these regulators is presented, and insights into the future direction of distributed voltage regulation are offered. © (2025), (Universidade do Porto - Faculdade de Engenharia). All rights reserved.