EAGER: Networking on Underwater Acoustic MIMO Links

墨西哥湾水下摄像机高度曝光的漏油现场直播是展示多媒体水下传感器网络在水下监视、海底勘探、视频辅助导航和环境监测等领域重要性的众多例子之一。然而，多媒体网络需要(I)比过去利用声学技术可用的数据速率高得多的数据速率和(Ii)灵活的协议设计。多输入多输出(MIMO)是一种传输技术，它可以利用水声传播的丰富散射结构提供的空间分集来提高数据速率或减少链路错误。到目前为止，研究界几乎没有实验数据来评估MIMO在真实水声链路中的潜力。该项目是一项早期研究工作，旨在收集数据并通过实验评估声学MIMO网络的潜力。正在建立一个试验台，以测量和模拟水下MIMO链路的传播特性，并了解基本的MIMO多路复用和分集权衡如何转化为可实现的传输速率和链路差错概率之间的权衡。该项目确定了MIMO链路的功能如何影响更高层网络协议的设计。由此得到的特征为设计一类集成的媒体接入控制和信令技术提供了信息，这些技术最佳地选择发射功率、MIMO传输模式和编码强度，以提高数据速率和降低误码率。所有收集到的数据都通过项目网站提供给研究界。

The highly-exposed live feed of the oil spill from underwater cameras in the Gulf of Mexico is one of many examples showcasing the importance of multimedia underwater sensor networks in fields such as underwater surveillance, undersea exploration, video-assisted navigation, and environmental monitoring. Multimedia networking, however, requires (i) much higher data rates than what has been available in the past with acoustic technology and (ii) flexible protocol design. Multiple-input-multiple-output (MIMO) is a transmission technique that may increase data rates or reduce link errors by leveraging the spatial diversity offered by the rich scattering structure of underwater acoustic propagation. To-date, little experimental data is available to the research community to assess the potential of MIMO gains in real underwater acoustic links. This project is an early-stage research effort to collect data and experimentally assess the potential of acoustic MIMO networking. A testbed is being built to measure and model the propagation characteristics of underwater MIMO links and understand how the fundamental MIMO multiplexing and diversity tradeoff translates into a tradeoff between achievable transmission rate and link error probability. The project identifies how the capabilities of MIMO links impact the design of higher layer networking protocols. The resulting characterization informs the design of a class of integrated medium access control and signaling techniques that optimally select the transmit power, MIMO transmission mode, and coding strength to improve data rates and reduce bit error rates. All collected data are being made available to the research community through the project website.