**Preface**

In recent years, the widespread use of wireless devices has seen significant growth in all sectors. Specifically, the post-COVID-19 situation has caused a huge revolution in the utilization of wireless devices across the globe. Advances are towards not only the number of devices in the network but also their applications, including sensors, Internet of Things (IoT) devices, mobile phones, and other wireless electronic gadgets, having a huge impact on maintaining global communication without any failure. It has been clearly witnessed that enormous power has been consumed by wireless devices when the entire world was using them during the pandemic. The varied utilization of wireless devices can be found not only among people working for industries but also among children and teachers working with schools and colleges and even beyond. As all wireless devices are battery-powered, energy is a critical issue, and it becomes essential to have the necessary energy management and control techniques and infrastructure in place to prolong the lifetime of both the individual device and the network. Hence, the present scenarios of a wireless environment have urged the research community to work more on energy efficiency issues on wireless devices. Hence, the articles in this reprint primarily target energy efficiency in wireless devices that focus on communication protocols, energy harvesting, energy management, device scheduling, edge computing, and so on for various wireless sensor, underwater, and IoT applications.

This reprint features 18 selected high-quality research articles spanning diverse domains in the field of energy-efficient wireless communication and networking. The contributions in this reprint collectively underscore the significance of energy optimization in wireless systems, illuminating innovative approaches, algorithms, and technologies that pave the way for sustainable and efficient wireless communication in various application scenarios.

Thus, this reprint brings together a rich tapestry of research that illuminates the ongoing efforts to design, optimize, and implement energy-efficient wireless communication and networking solutions. This reprint also encourages researchers to explore finer areas in the energy-efficient wireless network domain and provides a significant contribution to the research community to help further extend their areas of research.

> **R. Maheswar, M. Kathirvelu, and K. Mohanasundaram** *Editors*
