Underwater communication plays a crucial role in monitoring the aquatic environment on Earth. Due to their unique characteristics, underwater acoustic channels present unique challenges including lengthy signal transmission delays, limited data transfer bandwidth, variable signal quality, and fluctuating channel conditions. Furthermore, the reliance on battery power for most Underwater Wireless Acoustic Networks (UWAN) devices, coupled with the challenges associated with battery replacement or recharging, intensifies the challenges. Underwater acoustic communications are heavily constrained by available resources (e.g., very limited bandwidth, and limited energy storage). Consequently, the role of medium access control (MAC) protocol which distributes available resources among nodes is critical in maintaining a reliable underwater communication system. This study presents an extensive review of current research in MAC for UWAN. This study presents an extensive review of current research in MAC for UWAN. The paper explores the unique challenges and characteristics of UWAN, which are critical for the MAC protocol design. Subsequently, a diverse range of energy-efficient MAC techniques are categorized and reviewed. Potential future research avenues in energy-efficient MAC protocols are discussed, with a particular emphasis on the challenges to enable the broader implementation of the Green Internet of Underwater Things (GIoUT).

中文翻译：

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水下环境声学无线通信网络节能介质访问控制研究综述


水下通信在监测地球水生环境方面起着至关重要的作用。由于其独特的特性，水声通道带来了独特的挑战，包括漫长的信号传输延迟、有限的数据传输带宽、可变的信号质量和波动的通道条件。此外，大多数水下无线声学网络 （UWAN） 设备对电池供电的依赖，以及与电池更换或充电相关的挑战，加剧了挑战。水声通信受到可用资源的严重限制（例如，非常有限的带宽和有限的能量存储）。因此，在节点之间分配可用资源的介质访问控制 （MAC） 协议的作用对于维护可靠的水下通信系统至关重要。本研究对当前 UWAN 的 MAC 研究进行了广泛的回顾。本研究对当前 UWAN 的 MAC 研究进行了广泛的回顾。本文探讨了 UWAN 的独特挑战和特性，这些挑战和特性对 MAC 协议设计至关重要。随后，对各种节能 MAC 技术进行分类和回顾。讨论了节能 MAC 协议未来的潜在研究途径，特别强调了实现更广泛实施绿色水下物联网 （GIoUT） 所面临的挑战。