Collaborative Research: Distributed Electro-Mechanical Transmitters for Adaptive and Power-Efficient Wireless Communications in RF-Denied Environments

合作研究：分布式机电发射器，用于射频干扰环境中的自适应和高能效无线通信

• 批准号: 2104195
• 负责人: Swarup Bhunia
• 金额: $ 14.97万
• 依托单位: University of Florida
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2020
• 资助国家: 美国
• 起止时间: 2020-10-01 至 2023-06-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2104195&HistoricalAwards=false
• 关键词: Collaborative; Research; Distributed; Electro; Mechanical

Propagation of radio frequency (RF) electromagnetic waves becomes infeasible in certain situations, thus resulting in "RF-denied" environments. Examples include underground and deep-water facilities (mines, shelters, storage areas, tunnels, submarines, undersea cables, etc.). Recent events have highlighted the importance of wireless communications with such environments. A prominent example is the July 2018 rescue of a soccer team from the Tham Luang Nang Non cave in Thailand after they had been trapped underground for over two weeks. Such RF-denied environments are fundamentally produced by the short "skin depth" of electromagnetic waves within conductive media such as earth or seawater, which results in high attenuation. Fortunately, the skin depth increases as the frequency decreases, so extremely low frequency (ELF) radio waves in the kHz range can penetrate long distances in nominally RF-denied environments. For example, the skin depth in sea water is 7.1 m at 1 kHz, which would allow undersea communications to depths of about 30 m with reasonable transmit power levels if one could effectively couple ELF radio waves into the medium. However, conventional antennas are extremely large and impossible to deploy in this frequency range, while electrically-short antennas have very poor power efficiency. This project seeks to solve this fundamental problem by adopting a radically new approach to ELF antennas that is based on the mechanical motion of permanent magnets. The proposed research will have a broad impact on the availability of bidirectional wireless communications in RF-denied environments. Specifically, it will enable low-data-rate wireless links to be established using portable, robust, low-power, and low-cost devices. Such links are expected to have a multitude of applications in fields such as sensing and networking in underwater or underground environments, near-surface geophysics, atmospheric science, search and rescue operations, mining, and oil and gas exploration.The availability of portable low-power ELF transceivers would immediately enable communications within RF-denied environments by enabling bidirectional low-data-rate wireless links with the surface. While miniaturized and highly-sensitive ELF receivers are available, ELF transmitters (typically dipole or loop antennas) are the key obstacles for realizing such links since they are physically large and power-hungry. Thus, this project focuses on miniaturized and power-efficient ELF transmitters that enable bidirectional communications over short- and medium-range (up to about 1 km) wireless links in conductive media. In particular, the proposed research will explore a fundamentally new all-mechanical approach to ELF transmitter design that has the potential to enable efficient use of this region of the EM spectrum. The major intellectual contributions of this project focus on different aspects of this overall approach. They include: i) Proposing the concept of distributed all-mechanical transmitters based on synchronization over either wired or wireless networks and showing how it overcomes the key limitations of existing ELF transmitter architectures; ii) Creating a theoretical basis for the design of power-efficient wireless communications using systems that have significant mechanical inertia, thus linking the mathematics of information transfer over fading channels to the physics of the mechanical devices; and iii) Laying the first theoretical groundwork for the precise control of networked high-speed machines, which has the potential to dramatically advance the current state of the art by seamlessly modeling complex 3-D (dimensional) machine parameter variations and their tight coupling with high-speed machine vibrations and energy/power fluctuations within the transmitter network.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.

射频（RF）电磁波的传播在某些情况下变得不可行，从而导致“RF拒绝”环境。这方面的例子包括地下和深水设施（矿井、掩体、储存区、隧道、潜艇、海底电缆等）。最近的事件已经突出了与这样的环境的无线通信的重要性。一个突出的例子是2018年7月从泰国Tham Luang Nang Non洞穴救出一支足球队，他们被困地下两周多。这种拒绝RF的环境基本上是由电磁波在诸如地球或海水的导电介质内的短“趋肤深度”产生的，这导致高衰减。幸运的是，趋肤深度随着频率的降低而增加，因此kHz范围内的极低频（ELF）无线电波可以在名义上拒绝RF的环境中穿透长距离。例如，海水中的趋肤深度在1 kHz时为7.1 m，如果能够有效地将ELF无线电波耦合到介质中，则这将允许以合理的发射功率水平进行到大约30 m深度的海底通信。然而，传统的天线非常大，不可能部署在这个频率范围内，而电短天线的功率效率非常差。该项目旨在通过采用基于永磁体机械运动的全新ELF天线方法来解决这一根本问题。拟议中的研究将对射频拒绝环境中的双向无线通信的可用性产生广泛的影响。具体而言，它将使低数据速率无线链路能够使用便携式，鲁棒性，低功耗和低成本设备建立。这种链路有望在水下或地下环境中的传感和联网、近地表地球物理学、大气科学、搜索和救援行动、采矿以及石油和天然气勘探等领域得到广泛应用。便携式低功率ELF收发器的可用性将通过实现与地表的双向低数据速率无线链路，立即实现在RF拒绝环境中的通信。虽然小型化和高灵敏度的ELF接收器是可用的，但ELF发射器（通常是偶极或环形天线）是实现这种链路的关键障碍，因为它们物理上很大并且耗电。因此，该项目的重点是小型化和高能效的ELF发射机，能够在导电介质中通过短程和中程（约1公里）无线链路进行双向通信。特别是，拟议的研究将探索一种全新的全机械ELF发射机设计方法，该方法有可能有效利用该电磁频谱区域。该项目的主要智力贡献集中在这一总体方法的不同方面。它们包括：i）提出了基于有线或无线网络同步的分布式全机械发射机的概念，并展示了它如何克服现有ELF发射机架构的关键限制; ii）为使用具有显着机械惯性的系统设计节能无线通信奠定理论基础，从而将衰落信道上的信息传递的数学与机械设备的物理联系起来;以及iii）为网络化高速机器的精确控制奠定了第一个理论基础，通过无缝地模拟复杂的3D模型，（尺寸）机器参数变化及其与高速机器振动和能量的紧密耦合;该奖项反映了NSF的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。