A Survey on Routing Void Detection and Repair Technologies in Underwater Wireless Sensor Networks

Abstract

Underwater Wireless Sensor Networks (UWSNs) play a pivotal role in oceanic exploration. However, the stringent characteristics of the underwater acoustic channel, such as high latency and high dynamics, frequently cause routing voids (where data cannot be forwarded). This poses a core challenge to network reliability and efficiency. To systematically tackle this challenge, this paper analyzes 132 relevant studies to present a comprehensive synthesis of void-detection and mitigation techniques in UWSNs. This work proposes a classification framework based on technological evolution, categorizing void-handling techniques into three groups: (1) topology and geometric location-based routing methods, serving as the classical foundation; (2) Autonomous Underwater Vehicle (AUV)-aided approaches, which intervene by introducing external mobile entities; and (3) Artificial Intelligence (AI)-based methods, enabling intelligent avoidance by endowing nodes with learning and decision-making capabilities. This paper offers an in-depth analysis of key technologies, protocols, advantages, and limitations within each category. Furthermore, we systematically elucidate the evolutionary trajectory of void-handling technologies from rule-based passive bypass to predictive proactive intelligence. By establishing this perspective, we provide a strategic roadmap for constructing next-generation, robust, and adaptive underwater communication architectures, while exploring future research directions and challenges to guide subsequent researchers.