Magnetic Induction-Based Target Localization in Underground Endogenous Environment: Recent Challenges

Underground target localization technology facilitates various emerging applications in underground endogenous environments such as resource exploration and post-earthquake rescue, which are suffering from a significant reliability problem. Magnetic induction (MI) communication was thus introduced to enhance the underground wireless signal transmission, achieving more stable localization performance. However, in underground endogenous environments, the heterogeneous and non-uniform distribution of transmission media makes the MI-based underground target localization more complex and challenging. In this study, we proposed a systematic research roadmap for underground target localization technology to unlock the reliability potential, encompassing the channel models construction, localization features extraction, and feature fusion-based localization estimation. Specifically, tailored to the characteristics of heterogeneous and non-uniform medium distribution and the near-field coupling transmission of MI in underground endogenous environments, we first propose a multilayer medium channel model based on the Fresnel theoretical framework to acquire high-fidelity signal features. Subsequently, we summarize the latest research advancements in MI-based localization feature extraction schemes, based on which we integrate the spatial correlation of target shadow fading effects to extract positional features. Finally, we develop a multi-frequency, multi-scale signal feature fusion scheme to achieve precise target location estimation. In particular, we list and analyze the underlying challenges and related future issues in each direction.