Sensor networks provide services to a broad range of applications ranging from intelligence service surveillance to weather forecasting. While most of the sensor networks are terrestrial, Underwater Sensor Networks (USN) are an emerging area. One of the unavoidable and increasing challenges for modern USN technology is tolerating faults, i.e., accepting that hardware is imperfect, and coping with it. Fault Tolerance tends to have more impact in underwater than in terrestrial environment as the latter is generally more forgiving. Moreover, reaching the malfunctioning devices for replacement and maintenance under water is harder and more costly. The current paper is the first to provide an overview of fault-tolerant, particularly cross-layer fault-tolerant, techniques in USNs. In the paper, we present a systematic survey of the techniques, introduce a taxonomy of the Fault Tolerance tasks, present a categorized list of articles, and list the open research issues within the area.

中文翻译：

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水下传感器网络容错技术的系统回顾

传感器网络可为从情报服务监视到天气预报的广泛应用提供服务。尽管大多数传感器网络都是地面的，但水下传感器网络（USN）却是一个新兴领域。现代USN技术不可避免且日益严峻的挑战之一是容忍错误，即接受硬件不完善并加以应对。容错在水下的影响往往比在陆地环境中更大，因为后者通常更宽容。而且，到达故障设备以在水下进行更换和维护更加困难且成本更高。本论文是第一篇概述USN中的容错技术，尤其是跨层容错技术的文章。在本文中，我们对技术进行了系统的概述，