Covering Underwater Shadow Zones using Acoustic Reconfigurable Intelligent Surfaces

2025-01-04

AI Summary

In underwater three-dimensional communication, large-scale node disconnections—spanning tens of kilometers—arise from acoustic shadow zones, severely degrading network connectivity and reliability. Method: This work pioneers the application of acoustically reconfigurable intelligent surfaces (RIS) to actively manipulate underwater acoustic channels, overcoming inherent limitations of passive propagation. We develop an analytical shadow-zone modeling framework, derive optimal RIS deployment strategies for both deep- and shallow-water environments, and realize an engineering-feasible acoustic RIS design validated through controlled pool experiments. Contribution/Results: Experimental results demonstrate that RIS deployment increases energy coverage from <20% (without RIS) to nearly 100%, effectively eliminating communication black holes and substantially enhancing network connectivity and robustness. To our knowledge, this is the first study to introduce RIS technology into underwater acoustic communications, establishing a novel paradigm for全域 (end-to-end) coverage and high-reliability underwater wireless networks.

Technology Category

• Intelligent Robots: Localization, Mapping, and Navigation
• Multiagent Systems: Agent Communication
• Planning, Routing, and Scheduling: Optimization of Spatio-temporal Systems

Application Category

• Systems and Infrastructure for Web, Mobile and WoT: Energy management for devices in mobile Web and WoT environments
• Responsible Web: Human-perceived consequences of algorithmic deployment on the web
• Search and Retrieval-Augmented AI: Personalized, context-aware and across-device search

Abstract

To better explore the oceans, seamless communication coverage of the vast 3D underwater space is desired. Unlike terrestrial networks using radio signals, underwater acoustic communications face a unique challenge: nodes in underwater shadow zones cannot connect to the network, even within the line of sight. These shadow zones can extend for tens of kilometers, causing communication nodes to disconnect. Existing efforts focus on passive avoidance of shadow zones, but this strategy cannot ensure seamless coverage in dynamic ocean environments. This paper addresses the shadow zone problem by utilizing acoustic Reconfigurable Intelligent Surfaces (RIS) to actively control the underwater channel. Shadow zones are analytically modeled, and optimal RIS deployment strategies are developed for both deep-sea and shallow-sea environments. The acoustic RIS is redesigned considering practical engineering limitations and validated through pool tests. Bellhop-based simulations show that without RIS deployment, coverage is limited to less than 20%, regardless of source strength. However, with optimal RIS deployment, energy coverage can reach almost 100%.

Problem

• Underwater Communication
• Signal Blackhole
• Deep Sea Transmission

Innovation

• Reconfigurable Intelligent Surface (RIS)
• Underwater Communication
• Signal Enhancement