Special Issue “Wireless Sensor Networks: Technologies, Applications, Prospects”

Wireless sensor networks (WSN) have a long history of research and development. However, the emergence of new needs, applications, services, and various technological evolutions bring along new challenges. New scenarios such as energy systems, air and water quality monitoring systems, health monitoring systems, smart cities (traffic control, environmental monitoring, and parking system), sports, environmental monitoring, autonomous vehicles, and Industry 4.0, involve new challenges, both in the relationship between humans and technology, as well as in the technological challenges to be solved. Technological developments in communications, microelectronics, materials, and power consumption will also make it possible to solve problems that previously had no solution. WSNs are key central building blocks in the smart system that provides a reliable information channel for sensing and actuation at the required locations of the system at a low cost.

This Special Issue aims to collect and present all breakthrough research on all WSN technologies, novel designs, developments, and managements of smart systems with a focus on new applications. A total of eight papers in various topics of WSN and different applications and services are presented in this Special Issue. Very different scenarios are addressed, with several constraints that need to be resolved from unexpected scenarios such as Early Warning System for Pandemic Control to Aircraft systems, Industrial Wireless control systems, or Grid-Connected Photovoltaic Systems.

Society’s unpreparedness for the COVID-19 pandemic has raised the importance of early warning systems (EWS) to prevent similar future events and prepare governments, organizations, and individuals in advance. In [1], Tasic, I. and Cano, M.-D. propose a novel predictive location-based early warning system. The system is able to measure people’s density, people flow, and behavior in specific areas of indoor and outdoor environments. In addition, this system is applicable to different environments. Another scenario of particular relevance for the future of WSNs is that of Industry 4.0. Abdulrab, H. et al. [2] introduce a developed multipath routing model, which leads to cost-effective planning, low latency, and high reliability of industrial wireless mesh networks. The great challenge now is to move from simulation to the actual implementation of this type of network. Another complex scenario that requires the use of this type of network are photovoltaic (PV) systems. The design, monitoring, and control of PV systems are complex tasks that are often handled together, and they are made even more difficult by introducing features such as real-time, sensor-based operation, wireless communication, and multiple sensor nodes. This paper [3] proposes an integrated approach to handle these tasks, in order to achieve a system efficient in tracking the maximum power and injecting the energy from the PV modules to the grid in the correct way.

One aspect that will require great attention in the coming years is energy consumption and collection. In this paper [4], eight Energy Consumption of Beamforming and Cooperative Schemes for Aircraft are analyzed, with very interesting results for such a very complex scenario.

In addition, two types of networks of special interest due to their peculiar characteristics and their great future prospects are addressed: over-body networks and underwater networks. Rozas, A. et al. [5] analyze the performance of body are networks links during physical activity (standing, sitting, cycling, and walking) using three ISM bands: 433 MHz, 868 MHz and 2.4 GHz. They conclude that the receiver signal strength indicator (RSSI) metric is sufficient to exploit the periodicity of dynamic activities, without the need for any extra hardware resources. This conclusion will make it possible to establish predictions that favor the performance of this type of network. Additionally, on wearable devices, this paper [6] presents the design of a solution for extensive livestock monitoring in areas involved usually have difficulties accessing harsh orography and a lack of communications infrastructure. Their proposal is wearable equipment with inertial sensors, global positioning systems, wireless communications, and a Low-Power Wide Area Network infrastructure that can run with and without internet connection. Other very peculiar and interesting networks are the underwater sensor networks (UWSN). In this paper [7], authors studied and simulated the performance of an extremely important parameter for communication in UWSN, such as the acoustic channel capacity as a function of water temperature and salinity arise. The simulation results presented in this study through an improved algorithm to help to better the understanding of the underwater acoustic channel performance as a function of all of these factors.

Finally, one of the focuses of study in the WSN field is where and when data processing takes place. From computation at the node (edge computing), to computation in the cloud, depending on the requirements of latency, communications, and processing needs. In this aspect, Aleisa, M.A. et al. [8] propose a fine-grained data access control model based on the attribute-based encryption of the IoT–Fog–Cloud architecture to limit the access to sensor data and meet the authorization requirements, focusing on a fundamental aspect for the WSNs of the future of security.

As emerged in this editorial, Wireless Sensor Networks are one of the most exciting research topics in scientific community. New environments and applications need to be addressed with different restrictions. It is necessary to develop new designs for communications protocols, security, energy management, mobility, scalability, lifetime or localization. The papers published in the Special Issue “Wireless Sensor Networks: Technologies, Applications, Prospects” of Applied Sciences Journal entirely focus on this goal. Nevertheless, since the rapid growth of new technologies and materials, design methods and tools should follow this trend to continuously support designers of WSN for applying and exploiting related unique benefits.