This systematic review critically evaluates the current state and future potential of real-time, end-to-end smart, and automated irrigation management systems, focusing on integrating the Internet of Things (IoTs) and machine learning technologies for enhanced agricultural water use efficiency and crop productivity. In this review, the automation of each component is examined in the irrigation management pipeline from data collection to application while analyzing its effectiveness, efficiency, and integration with various precision agriculture technologies. It also investigates the role of the interoperability, standardization, and cybersecurity of IoT-based automated solutions for irrigation applications. Furthermore, in this review, the existing gaps are identified and solutions are proposed for seamless integration across multiple sensor suites for automated systems, aiming to achieve fully autonomous and scalable irrigation management. The findings highlight the transformative potential of automated irrigation systems to address global food challenges by optimizing water use and maximizing crop yields.

Sensing and communication technology has been used successfully in various event monitoring applications over the last two decades, especially in places where long-term manual monitoring is infeasible. However, the major applicability of this technology was mostly limited to terrestrial environments. On the other hand, underwater wireless sensor networks (UWSNs) opens a new space for the remote monitoring of underwater species and faunas, along with communicating with underwater vehicles, submarines, and so on. However, as opposed to terrestrial radio communication, underwater environment brings new challenges for reliable communication due to the high conductivity of the aqueous medium which leads to major signal absorption. In this paper, we provide a detailed technical overview of different underwater communication technologies, namely acoustic, magnetic, and visual light, along with their potentials and challenges in submarine environments. Detailed comparison among these technologies have also been laid out along with their pros and cons using real experimental results.

A swarm of Autonomous Underwater Vehicles (AUVs) can provide richer spatial-temporal information than the traditional single-robot system, which can be used for underwater mapping, exploration, target tracking, among others. However, the limitation of AUVs’ battery cannot support persistent services, which restricts AUVs’ operating range and mission duration. In this paper, a mobile underwater charging solution is developed that can continuously recharge a swarm of AUVs by using a wireless mobile charger. Magnetic induction-based communication and wireless energy transfer are employed. This paper first shows that by using tri-axis coils, reliable wireless communication and wireless energy transfer without coil orientation losses can be obtained. After that, wireless communication, motion control, and wireless energy transfer are jointly designed for a swarm of mission-driven AUVs. In particular, optimal continuous motion controllers are developed for AUVs to avoid intra-swarm collisions and networking protocols are designed to optimally allocate resources for wireless communication and wireless energy transfer. The proposed approach can guide AUVs to their destinations, while maintaining wireless network integrity and maximizing wireless energy transfer efficiency, upon which the constraints on AUVs’ batteries can be eliminated and cheaper and smaller AUVs can be employed for various underwater applications.

The UnderWater Acoustic (UWA) communication is the foundation for oceanic information applications. However, existing UWA systems suffer from low data rate problem. Although the Multiple Input Multiple Output (MIMO) scheme is proved to be able to increase channel capacity in many terrestrial scenarios, the high cost and complexity of acoustic MIMO significantly limit its usage. Recently, the acoustic reconfigurable intelligent surfaces (acoustic RIS) concept has been proposed to address the aforementioned problem. In this paper, with the real-world constraints taken into consideration, three key components of the acoustic RIS are designed to realize the underwater RIS concept, including the new acoustic RIS hardware, the ultra-wideband (UWB) beamforming, and practical operation protocol. Specifically, a completely new hardware design of acoustic RIS is first provided, since existing electromagnetic RIS designed for terrestrial environments do not work for underwater acoustic waves. Then, the UWB beamforming solution is developed, since underwater acoustic RIS need to control the acoustic signals, whose bandwidth is comparable to its carrier frequency. Finally, the practical operation protocol is developed to realize the acoustic RIS functionalities in complex underwater environment. The acoustic RIS design is validated through both COMSOL multiphysics simulations and end-to-end Bellhop-based simulations.

Magnetic induction communication (MIC) demonstrates high penetration efficiency and low propagation loss in extreme environments. It is used in underground and underwater environments to enable critical applications that cannot be achieved by using terrestrial wireless techniques. This article studies the channel and antenna modeling for MIC in inhomogeneous environments, where a transmitter and a receiver are in two different media. This problem finds a large number of practical applications such as communicating with wireless sensors in the soil, water, walls, and the human body using a wireless device in the air. This article develops a joint channel and antenna model considering the inhomogeneity of the surrounding environments. An exact full-wave model and a near field approximation model are developed and evaluated to show the characteristics of this novel wireless technique as well as the limitations of existing solutions. Using the communication with underground sensors as an example, the results show that the path loss of MIC strongly depends on the propagation media which is drastically different from electromagnetic wave-based wireless communications in terrestrial environments. Also, we find that the MIC channel in inhomogeneous media exhibits non-reciprocity due to different transmission coefficients through the boundary. Moreover, the boundary can be neglected when the carrier frequency is sufficiently low. The developed model provides a tool to design wireless sensor networks in inhomogeneous extreme environments.

Wireless sensors or robots in metal-constrained environments leverage through-metal wireless communications to send data and receive instructions. It is well-known that wireless radio frequency (RF) signals cannot penetrate through metal efficiently, which prevents us from applying existing wireless solutions. Moreover, most applications, e.g., metal inspection robots in an oil pipeline, require noncontact wireless communications, where the ultrasonic signals do not work. To this end, we propose to use magnetic induction communication to provide a reliable and flexible solution for wireless sensor and robotic networks in metal-constrained environments. We consider the transceivers are located on two different sides of a metal wall. Then, we develop an analytical model to obtain the optimal configurations of the magnetic coil and the carrier frequency to maximize the communication channel capacity. The received power and wireless channel bandwidth are studied. The results show that the optimal carrier frequency is around 1 kHz. In addition, we study the negative effects caused by coil misalignment and interference, which are circumvented by leveraging a coil array with optimal receiving strategy. The results are evaluated using numerical simulation and verified by finite element method-based simulation.