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

咸水是导体，因此，目前只有基于极低频率无线电的通信技术在水下工作：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，但比无线电波慢五个数量级。这会引起严重的混响和码间干扰，特别是在长距离上。现有的声学调制解调器只能实现几个100s比特/秒的数据速率。研究小组调查了Turbo均衡的发展-这是一种不仅可以减少符号间干扰，还可以利用分集进行纠错的技术。此外，恶劣的多普勒效应随机扭曲了波形的时间尺度，如果不进行动态补偿，这可能会对通信造成灾难性的影响。该团队开发了一种涡轮均衡器，可以持续跟踪并补偿多普勒效应，然后集成了该算法构建了一个无线水下调制解调器原型。该调制解调器样机经过了美国海军广泛的实地测试，表明它具有高度的可靠性，而且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，是世界上95%以上的生物物质的家园？S，并拥有其绝大多数的矿产和化石资源。探索、利用和保护这一空间对社会非常重要，但海底的任何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在环境监测、科学勘探、海洋可再生能源发电、商业捕鱼、国防、航道保护与安全、资源发现和生产等多个领域产生深远影响。军事、资源发现和生产行业将从这项技术中受益匪浅。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.