I-Corps: OceanComm: Reliable, High Data Rate Underwater Communications and Positioning

盐水是导体，因此，目前只有极低频的基于无线电的水下通信技术才能工作：这些技术无法支持GPS， Wi-Fi或任何高数据速率通信。在海底无线传输信息的唯一实用方法之一是通过声波传播。声波可以传播数百英里，但比无线电波慢5个数量级。这会引起严重的混响和符号间干扰，特别是在长距离上。现有的声学调制解调器只能达到每秒几百比特的数据速率。研究小组研究了turbo均衡技术的发展，该技术不仅可以减轻符号间的干扰，还可以利用分集进行纠错。此外，严重的多普勒效应随机扭曲波形的时间尺度，如果不进行动态补偿，这对通信可能是灾难性的。该团队开发了一种涡轮均衡器，可以持续跟踪和补偿多普勒效应，然后建立了一个集成该算法的无线水下调制解调器原型。调制解调器原型已经经历了广泛的美国海军现场测试，证明它既高度可靠，又比现有的商用调制解调器快100倍。海洋覆盖了地球表面的71%，承载着90%的国际贸易，是世界95%以上人口的家园？美国是世界上生物量最大的国家，并拥有其绝大多数矿产和化石资源。对这一空间的探索、利用和保护对社会很重要，但任何海底协调努力都需要定位、导航和通信。因此，水下通信的技术创新将对环境监测、科学勘探、海洋可再生能源发电、商业捕捞、国防、航道保护与安全、资源发现与生产等诸多领域产生深远影响。军事、资源发现和生产工业是将从这项技术中大大受益的广泛用户基础。该项目汇集了来自信号处理、通信和海洋学的研究人员，为水下环境提供前所未有的能力。

Salt water is a conductor and as a result, currently only extremely low frequency radio based communication technologies work underwater: These have not been able support GPS, Wi-Fi, or any high data rate communications.One of the only practical methods to carry information wirelessly undersea is through acoustic wave propagation. Acoustic waves can travel for hundreds of miles, but are five orders of magnitude slower than radio waves. This gives rise to severe reverberation and inter-symbol interference, especially over long distances. Existing acoustic modems can only achieve data rates of a few 100s of bits/second. The research team investigated the development of turbo equalization - a technique that not only mitigates inter-symbol interference but also leverages the diversity for error correction. Additionally harsh Doppler effects warp the time-scale of the waveform randomly, which can be catastrophic for communications if not compensated dynamically. This team developed a turbo equalizer that constantly tracks and compensates for Doppler effects and then built a wireless underwater modem prototype integrating this algorithm. The modem prototype has undergone extensive US Navy field-tests demonstrating that it is both highly reliable and 100 times faster than existing commercial modems. The oceans cover 71% of the Earth's surface, carry 90% of international trade, are the home for over 95% of the world?s living biomass, and hold the vast majority of its mineral and fossil resources. The exploration, utilization and protection of this space is important to society, but any coordinated effort undersea will require positioning, navigation and communication. Therefore, technical innovation in underwater communication will have profound impact on many fronts: environmental monitoring, scientific exploration, marine renewable energy generation, commercial fishing, defense, shipping route protection and security, and resource discovery and production.The military, resource discovery and production industries are among the broad user-base that would benefit greatly from this technology. This project brings together researchers from signal processing, communications, and oceanography to provide unprecedented capabilities to the underwater environment.