Digital Transmission Concepts for Underground Communications UsingMagnetic Induction

无线地下传感器网络(WUSNs)的目标是在地下介质中建立高效的无线通信。为了克服无线传感器网络中非常恶劣的传播条件，提出了一种基于磁感应(MI)的信号传输方案。由于MI技术对环境变化的脆弱性要低得多，因此与传统的基于电磁波的传输相比，MI技术已被证明在可实现的数据速率和覆盖方面改善了系统性能。在以前的工作中，已经对MI-WUSN的网络优化和信号处理算法的设计进行了初步的研究。通常，所提出的方法旨在分别提高点对点传输的可实现数据速率和具有多个传感器节点的网络的理论吞吐量。在该项目的这一部分，将通过引入基于多线圈的收发信机来进一步提高数字传输的性能。这种方法是由多输入多输出(MIMO)系统在射频通信中使用多天线来实现高分集和多路复用增益而产生的。此外，为了在接近地面的地下介质中以足够的能量运行，传感器节点需要收集能量并通过无线能量传输的方式相互支持，这也将被研究。无线传感器网络的一项重要任务是对人和物体进行定位。为了在MI-WUSN中实现这一功能并提供足够的精度，将开发新的定位算法，其考虑到MI-WUSN的典型信号传播特性。

The objective of Wireless Underground Sensor Networks (WUSNs) is to establish an efficient wireless communication in the underground medium. A magnetic induction (MI) based signal transmission scheme has been proposed to overcome the very harsh propagation conditions in WUSNs. Due to a much lower vulnerability to the environmental changes, the MI technique has been shown to improve the system performance in terms of achievable data rates and coverage compared to the traditional electromagnetic (EM) wave based transmission. In the previous works, the first steps in network optimization and design of signal processing algorithms for MI-WUSNs have been made. Typically, the proposed approaches aim at increasing the achievable data rates for point-to-point transmissions and the theoretical throughput of a network with multiple sensor nodes, respectively. In this part of the project, the performance of the digital transmission will be further improved by introducing multiple coils based transceivers. This approach is motivated by the multiple-input multiple-output (MIMO) systems in RF communications using multiple antennas, which enable high diversity and multiplexing gains. Furthermore, for operating with sufficient energy in the underground medium with limited access to the surface, sensor nodes need to harvest energy and support each other by means of wireless power transfer, which will be investigated as well. An important task of wireless sensor networks is the localization of persons and objects. In order to enable this functionality in MI-WUSNs and to provide a sufficient level of accuracy, novel localization algorithms will be developed, which take into account the typical signal propagation characteristics of MI-WUSNs.