Wireless Underground Communication Research Articles

Taking Wireless Underground: A Comprehensive Summary

The tremendous potential of sensing and communication technologies has been explored and implemented for different remote event monitoring applications over the past two decades. However, the applicability of sensing and communication technologies is not necessarily limited to aboveground environments—it is also implementable and applicable for subterranean, underground scenarios. However, as opposed to air medium, underground communication medium is quite harsh due to the presence of heterogeneous underground materials along with underground aqueous components. In this article, we provide a technical overview of different underground wireless communication technologies, namely radio, acoustic, magnetic, and visible light, along with their potentials and challenges for several underground applications. We also lay out a detailed comparison among these technologies along with their pros and cons using detailed experimental results.

A Novel Polar Code Construction for Magnetic Induction-Based Wireless Underground Communications

A Novel Polar Code Construction for Magnetic Induction-Based Wireless Underground Communications

Novel communication system for buried water pipe monitoring using acoustic signal propagation along the pipe

PurposeWireless sensor networks (WSN), as a solution for buried water pipe monitoring, face a new set of challenges compared to traditional application for above-ground infrastructure monitoring. One of the main challenges for underground WSN deployment is the limited range (less than 3 m) at which reliable wireless underground communication can be achieved using radio signal propagation through the soil. To overcome this challenge, the purpose of this paper is to investigate a new approach for wireless underground communication using acoustic signal propagation along a buried water pipe.Design/methodology/approachAn acoustic communication system was developed based on the requirements of low cost (tens of pounds at most), low power supply capacity (in the order of 1 W-h) and miniature (centimetre scale) size for a wireless communication node. The developed system was further tested along a buried steel pipe in poorly graded SAND and a buried medium density polyethylene (MDPE) pipe in well graded SAND.FindingsWith predicted acoustic attenuation of 1.3 dB/m and 2.1 dB/m along the buried steel and MDPE pipes, respectively, reliable acoustic communication is possible up to 17 m for the buried steel pipe and 11 m for the buried MDPE pipe.Research limitations/implicationsAlthough an important first step, more research is needed to validate the acoustic communication system along a wider water distribution pipe network.Originality/valueThis paper shows the possibility of achieving reliable wireless underground communication along a buried water pipe (especially non-metallic material ones) using low-frequency acoustic propagation along the pipe wall.

Recent Advancements in IoT Implementation for Environmental, Safety, and Production Monitoring in Underground Mines

Internet of Things (IoT) technology has been widely used for real-time monitoring of the environment, safety and production in underground mines. This paper presents the basic structure of a Mine Internet of Things (MIoT) system based on a widely used three-layer IoT architecture, classifies types of sensors commonly used in underground mines by specific application, and introduces available wired and wireless communication technologies and network topologies that can be applied in underground mines. This paper provides a comprehensive review of recent developments in IoT applications in underground mines to monitor various environmental parameters, including mine gas and dust concentrations, temperature, humidity and airflow, groundwater, ground support and seismic activity. MIoT applications for fire and hazard detection, personnel and equipment positioning, and production safety management have also been investigated. This paper highlights key challenges for the broad application of IoT technology in underground mines such as operation disruption, additional investment, limited battery life, poor quality of underground communication, and difficulty in data management. Further research on novel advanced techniques, such as self-powered sensors, MIoT standardization and underground wireless communication technologies, is essential to improve the applicability and effectiveness of IoT applications in underground mines.

Analysis of Acoustic Signal Propagation for Reliable Digital Communication along Exposed and Buried Water Pipes

Wireless sensor networks (WSN) have emerged as a robust and cost-effective solution for buried pipeline monitoring due to the low cost (a maximum of a few tens of UK pounds (GBP)), low power supply capacity (in the order of 1 watt/hour) and small size (centimetre scale) requirements of the wireless sensor nodes. One of the main challenges for WSN deployment, however, is the limited range of underground data communication between the wireless sensor nodes of less than 3 m, which subsequently increases deployment costs for a utility owner for buried pipeline monitoring. A promising alternative to overcome this limitation is using low-frequency (<1 kHz) acoustic signal propagation along the pipe. This paper examines the feasibility of using low-frequency acoustic signal propagation along exposed and buried medium-density polyethylene (MDPE) pipes and makes predictions of the potential distances at which reliable data communication can be achieved. Quantification of the acoustic attenuation was performed using both analytical and numerical models in addition to laboratory and field experiments. The predicted acoustic data communication distance ranged between approximately 18 m for an exposed and approximately 11 m for a buried MDPE pipe. These results demonstrate the feasibility of using low-frequency acoustic signal propagation for achieving reliable wireless underground communication.

Wireless Communication for Drilling Using Acoustic Wave Based on MIMO-OFDM

Underground data transmission methods are divided into wired and wireless. Wired transmission includes traditional cable and optical fiber. Wireless transmission includes pressure wave and electromagnetic wave. The limitation of the down-hole data upload rate has become the bottleneck. The wireless transmission system of an acoustic wave using a drilling fluid channel is studied. Drilling fluid channel is a multi-path channel with frequency selective fading characteristics. In the process of drilling, the shape of drill string is spatial spiral bending. This paper provides an exhaustive research in OFDM-MIMO for drilling acoustic telemetry system. The characteristics of drilling fluid channel are discussed. The performances of multiple input multiple output (MIMO), multiple input single output (MISO) and single input single output (SISO) wireless acoustic transmission systems are compared. Acoustic waves transmitted along the drilling fluid channel can realize underground wireless communication with a high transmission rate and a low bit error rate.

SmartCrawler: A Size-Adaptable In-Pipe Wireless Robotic System with Two-Phase Motion Control Algorithm in Water Distribution Systems.

Incidents to pipes cause damage in water distribution systems (WDS) and access to all parts of the WDS is a challenging task. In this paper, we propose an integrated wireless robotic system for in-pipe missions that includes an agile, maneuverable, and size-adaptable (9-in to 22-in) in-pipe robot, "SmartCrawler", with 1.56 m/s maximum speed. We develop a two-phase motion control algorithm that enables reliable motion in straight and rotation in non-straight configurations of in-service WDS. We also propose a bi-directional wireless sensor module based on active radio frequency identification (RFID) working in 434 MHz carrier frequency and 120 kbps for up to 5 sensor measurements to enable wireless underground communication with the burial depth of 1.5 m. The integration of the proposed wireless sensor module and the two-phase motion controller demonstrates promising results for wireless control of the in-pipe robot and multi-parameter sensor transmission for in-pipe missions.

Bio-inspired vibrational wireless underground communication system

The internet of the underground things (IoUT) is an emerging field that concerns connected underground sensing nodes and can find applications in various fields such as geotechnical engineering, precision agriculture, and search and rescue operations. The complex underground environment and multiphase nature of the soil pose challenges to wireless underground communication. Most existing studies on wireless underground communication focus on the use of electromagnetic waves. However, as a highly lossy material for electromagnetic waves, soil can limit the range and reliability of data transmission. Inspired by subterranean animals that rely on vibrations or seismic waves for underground communication, the prototype system developed in this study is based on vibration. This system includes a bio-inspired vibrating source, a micro-electromechanical system (MEMS) accelerometer, a micro-controller, and a set of algorithms for encoding and decoding information. Specifically, the mole rats-inspired source is small in size, low in cost, and energy-efficient. An on-off-keying decoding algorithm enhanced with an error-correction algorithm is found to be robust in transmitting textual and imaginary information. With the current design, a maximum transmission bit rate of 16–17 bits per second and a transmission distance of 80 cm can be achieved. The bit error ratio is as low as 0.1%, demonstrating the robustness of the algorithms. The performance of the developed system shows that seismic waves produced by vibration can be used as an information carrier and can potentially be implemented in the IoUT.

Magneto-Mechanical Transmitters for Ultralow Frequency Near-Field Data Transfer

Electromagnetic signals in the ultralow frequency (ULF) range below 3 kHz are well suited for underwater and underground wireless communication thanks to low signal attenuation and high penetration depth. However, it is challenging to design ULF transmitters that are simultaneously compact and energy efficient using traditional approaches, e.g., using coils or dipole antennas. Recent works have considered magneto-mechanical alternatives, in which ULF magnetic fields are generated using the motion of permanent magnets, since they enable extremely compact ULF transmitters that can operate with low energy consumption and are suitable for human-portable applications. Here we explore the design and operating principles of resonant magneto-mechanical transmitters (MMT) that operate over frequencies spanning a few 10 s of Hz up to 1 kHz. We experimentally demonstrate two types of MMT designs using both single-rotor and multirotor architectures. We study the nonlinear electro-mechanical dynamics of MMTs using point dipole approximation and magneto-static simulations. We further experimentally explore techniques to control the operation frequency and demonstrate amplitude modulation up to 10 bits-per-second. We additionally demonstrate how using oppositely polarized MMT modules can permit systems that have low dc-field but do not sacrifice the ac magnetic field produced.

Research on Optimization Measures of Zigbee Network Connection in an Imitated Mine Fading Channel

Based on the background of a mine, this study aimed to improve underground wireless communication. The study selected Zigbee technology from many wireless technologies as the basis, expounded the technical advantages and disadvantages, and addressed its disadvantages. First, the modulation technology of Zigbee was improved. This article selects and describes O-QPSK technology from three modulation technologies, thereby addressing the synchronization difficulties caused by inherent technical reasons, and proposes a modulation method based on feedforward timing. Moreover, excellent performance was achieved in the follow-up simulation experiment. For networking problems, a series of mechanisms are proposed to address several problems in large-scale networking: node offline, energy waste, signal delay, etc. This article proposes five main mechanisms and an improved protocol from two significant perspectives. The problem of node disconnection is divided into two parts. Considering the different status of edge nodes and important nodes in the network, three mechanisms are proposed for edge nodes for disconnection detection and self-repair, and two mechanisms are proposed for essential nodes. This can compensate for the loss caused by the disconnection of essential nodes at a specific time. For network energy waste, an Improved-LEACH protocol is proposed to alleviate the signal delay problem. The performance of the five mechanisms and one protocol was verified in a simulation test, and the performance was reasonable and in line with expectations.

Gaped Two-Loop Antenna-Based Magnetic Transceiver With an Empirical Model for Wireless Underground Communication

This paper presents a practical low-power, low-frequency magnetic induction (MI) transceiver based on symmetrical gaped two-loop antennas with an empirical circuit model for wireless underground communication. Because of the quasi-two-dimensional loop antennas for the transmitter (Tx) and the receiver (Rx), the tailored hardware platform is not only simple, but can be readily extended to a mutually orthogonal 3-D scheme. Through a mixed model of actual measurement data and theoretical parameters, we developed the two-loop antenna with the space of the antenna radius optimized for energy efficiency. The Tx power almost doubles that of the single Tx one, which provides channel expansion as well as system stability in terms of the Tx current level. Accordingly, the Rx signal is considerably increased by 9.5 dB in contrast with a typical single-Tx single-Rx configuration. Moreover, we used empirical-based modeling for a reliable electrical model. The empirical mutual inductance, which was modeled in a 25 m corridor, resulted in a channel correction factor of 0.86, showing that the signal intensity was reduced by 14% in the underground corridor compared to the free space. A maximum range of 68 m under a SNR of 9.5 dB and a path loss of 100.7 dB on a load of $50~\Omega $ at 34.5 dBm were predicted from the model. In addition, this study confirmed the system feasibility by a SNR of 8.7 dB in a practical lossy environment between two floors, where its value was converted into a MI channel at a distance of 70 m in the underground corridor.

Бюджет подземного канала беспроводной связи сквозь горную породу

At present, radio stations of the very-long wave (VLW) range with a power of several hundred and thousands of watts with large antennas (hundreds and thousands of meters) are used for wireless through-the-earth communication in mines. Such radio stations allow providing a one-way communication channel informing miners about emergencies. In addition, in recent years, portable radio stations of the medium-frequency (MF) band have also become widespread, which use monofil or bifilar lines laid along mine tunnel for communication, and electrically small antennas. In this regard, an urgent scientific task is to estimate the budget of an underground wireless communication channel wireless through-the-earth using a portable radio station and electrically small antennas. Purpose of the article: to analyze the characteristics of through-the-earth communication channels in the range from 1 kHz to 10 MHz, to compare the budget and signal-to-noise ratio of the MF channel with the channels in the low frequency (LF) band. As a result, the losses in the through-the-earth communication channel in the range from 1 kHz to 10 MHz are estimated: at the output of the transmitting antenna, at the receiving point, at the output of the receiving antenna. A detailed calculation of the budget at a frequency of 1 MHz for a radio path with a length of 100 meters for various values of electrical conductivity characteristic of rocks is presented. Attention is focused on the antenna efficiency and its contribution to the budget of the communication channel. It is shown that two opposite factors: a drop in the antenna efficiency and a decrease in losses in a semiconducting medium with a decrease in the operating frequency, lead to the emergence of optimal radio frequencies, depending on various values of the electrical conductivity of rocks, which are semiconducting media. Practical relevance. The obtained research results justifiably confirm the effectiveness of using small-sized (including portable) radio stations of the MF band for organizing two-way through-the-earth communication between levels in mines. The obtained optimal frequencies make it possible to select the operating range in mines located in rocks with different electrophysical characteristics.

A Survey on Subsurface Signal Propagation

Wireless Underground Communication (WUC) is an emerging field that is being developed continuously. It provides secure mechanism of deploying nodes underground which shields them from any outside temperament or harsh weather conditions. This paper works towards introducing WUC and give a detail overview of WUC. It discusses system architecture of WUC along with the anatomy of the underground sensor motes deployed in WUC systems. It also compares Over-the-Air and Underground and highlights the major differences between the both type of channels. Since, UG communication is an evolving field, this paper also presents the evolution of the field along with the components and example UG wireless communication systems. Finally, the current research challenges of the system are presented for further improvement of the WUCs.

A city-wide experimental testbed for the next generation wireless networks

To facilitate research in dynamic spectrum access, 5G, vehicular networks, underground wireless communications, and radio frequency machine learning, a city-wide experimental testbed is developed to provide realistic radio environment, standardized experimental configurations, reusable datasets, and advanced computational resources. The testbed contains 5 cognitive radio sites, and covers 1.1 square miles across two campuses of the University of Nebraska-Lincoln and a public street in the city of Lincoln, Nebraska. Each site is equipped with a 4x4 MIMO software-defined radio transceiver with 20Gbps fronthaul connectivity. Additional cognitive radio transceivers with an underground 2x2 MIMO antenna are included in a site. High speed fronthaul network based on dedicated fiber connects the 5 sites to a cloud-based central unit for data processing and storage. The testbed provides researchers rich computational resources such as arrays of CPUs and GPUs at the cloud and FPGAs at both the edge and fronthaul network. Developed via the collaboration of the university, city, and industrial partners, this testbed will facilitate education and researches in academic and industrial communities.

Wireless Underground Sensor Networks Path Loss Model for Precision Agriculture (WUSN-PLM)

Despite a large number of applications in the field of health care, military, ecology or agriculture, the Wireless Underground Sensor Network (WUSN) faces the problem of wireless Underground Communication (WUC) which largely attenuate the signal on the ground. For the case of precision agriculture, the motes are buried and they have to check the good growth of plants by verifying data like the water content. However, due to soil composition, the wave signal is attenuated as it travels across the ground. Thus, before a real deployment of WUSN, the prediction of the path loss due to signal attenuation underground is an important asset for the good network functioning. In this paper, we proposed a WUSN path loss for precision agriculture called WUSN-PLM. To achieve it, the proposed model is based on an accurate prediction of the Complex Dielectric Constant (CDC). WUSN-PLM allows evaluating the path loss according to the different types of communication (Underground-to-Underground, Underground to Aboveground and Aboveground to Underground). On each communication type, WUSN-PLM takes into account reflective and refractive wave attenuation according to the sensor node burial depth. To evaluate WUSN-PLM, intensive measurements on real sensor nodes with two different pairs of transceivers have been conducted on the botanic garden of the University Cheikh Anta Diop in Senegal. The results show that the proposed model outperforms the existing path loss models in different communication types. The results show that our proposed approach can be used on real cheap sensor with 87.13% precision and 85% balanced accuracy.

Zenneck Waves in Decision Agriculture: An Empirical Verification and Application in EM-Based Underground Wireless Power Transfer

In this article, the results of experiments for the observation of Zenneck surface waves in sub GHz frequency range using dipole antennas are presented. Experiments are conducted over three different soils for communications distances of up to 1 m. This empirical analysis confirms the existence of Zenneck waves over the soil surface. Through the power delay profile (PDP) analysis, it has been shown that other subsurface components exhibit rapid decay as compared to the Zenneck waves. A potential application of the Zenneck waves for energy transmission in the area of decision agriculture is explored. Accordingly, a novel wireless through-the-soil power transfer application using Zenneck surface waves in electromagnetic (EM) based wireless underground communications is developed.

On-Site and External Energy Harvesting in Underground Wireless

Energy efficiency is vital for uninterrupted long-term operation of wireless underground communication nodes in the field of decision agriculture. In this paper, energy harvesting and wireless power transfer techniques are discussed with applications in underground wireless communications (UWC). Various external wireless power transfer techniques are explored. Moreover, key energy harvesting technologies are presented that utilize available energy sources in the field such as vibration, solar, and wind. In this regard, the Electromagnetic (EM)- and Magnetic Induction (MI)-based approaches are explained. Furthermore, the vibration-based energy harvesting models are reviewed as well. These energy harvesting approaches lead to design of an efficient wireless underground communication system to power underground nodes for prolonged field operation in decision agriculture.

Wireless Underground Communications in Sewer and Stormwater Overflow Monitoring: Radio Waves through Soil and Asphalt Medium

Storm drains and sanitary sewers are prone to backups and overflows due to extra amount wastewater entering the pipes. To prevent that, it is imperative to efficiently monitor the urban underground infrastructure. The combination of sensors system and wireless underground communication system can be used to realize urban underground IoT applications, e.g., storm water and wastewater overflow monitoring systems. The aim of this article is to establish a feasibility of the use of wireless underground communications techniques, and wave propagation through the subsurface soil and asphalt layers, in an underground pavement system for storm water and sewer overflow monitoring application. In this paper, the path loss analysis of wireless underground communications in urban underground IoT for wastewater monitoring has been presented. The dielectric properties of asphalt, sub-grade aggregates, and soil are considered in the path loss analysis for the path loss prediction in an underground sewer overflow and wastewater monitoring system design. It has been shown that underground transmitter was able to communicate through thick asphalt (10 cm) and soil layers (20 cm) for a long range of up to 4 km.

Design and Implementation of Magnetic Induction based Wireless Underground Communication System Supporting Distance Measurement

Design and Implementation of Magnetic Induction based Wireless Underground Communication System Supporting Distance Measurement

Subsurface MIMO: A Beamforming Design in Internet of Underground Things for Digital Agriculture Applications

In underground (UG) multiple-input and multiple-output (MIMO), transmit beamforming is used to focus energy in the desired direction. There are three different paths in the underground soil medium through which the waves propagate to reach the receiver. When the UG receiver receives a desired data stream only from the desired path, then the UG MIMO channel becomes a three-path (lateral, direct, and reflected) interference channel. Accordingly, the capacity region of the UG MIMO three-path interference channel, and the degrees of freedom (multiplexing gain of this MIMO channel) requires careful modeling. Therefore, expressions are required for the degrees of freedom of the UG MIMO interference channel. The underground receiver needs to perfectly cancel the interference from the three different components of the EM waves propagating in the soil medium. This concept is based upon reducing the interference of the undesired components to a minimum level at the UG receiver using the receive beamforming. In this paper, underground environment-aware MIMO using transmit and receive beamforming has been developed. The optimal transmit and receive beamforming, combining vectors under minimal intercomponent interference constraints, are derived. It is shown that UG MIMO performs best when all three components of the wireless UG channel are leveraged for beamforming. The environment-aware UG MIMO technique leads to three-fold performance improvements and paves the way for design and development of next-generation sensor-guided irrigation systems in the field of digital agriculture. Based on the analysis of underground radio-wave propagation in subsurface radio channels, a phased-array antenna design is presented that uses water content information and beam-steering mechanisms to improve efficiency and communication range of wireless underground communications. It is shown that the subsurface beamforming using phased-array antennas improves wireless underground communications by using the array element optimization and soil–air interface refraction adjustment schemes. This design is useful for subsurface communication system where sophisticated sensors and software systems are used as data collection tools that measure, record, and manage spatial and temporal data in the field of digital agriculture.