## 1 Introduction  
The profound transformation driven by the need for deeper and faster decarbonization is changing the energy world while creating new challenges, both on the supply and demand sides [1]. Particularly in Europe, but also around the world, the power sector is strongly involved in this process and will deliver a significant part of the necessary efforts [2]. In this context, the energy infrastructure needs to be enhanced and digitalized to cope with the deployment of renewable sources, increased decentralization, and electrification of end users and active customers, ensuring, at the same time, energy network stability, security, and resilience. Many factors are influencing this transition. On the one hand, the electricity generated from renewable sources is predominantly variable in its nature, with the need for the grids to manage power flows more promptly and efficiently to support the integration of less predictable energy production while maintaining the quality of supply [3; 4]. On the other hand, grid interoperability with distributed resources--including small photovoltaic (PV) systems and storage, energy communities, and \"prosumers\"--is one of the fundamental pillars of grid development [5]. Moreover, energy consumption patterns are changing too, due to the growth of new forms of energy demand in building, transport, and industry sectors, with high variability and high power rating, such as the charging of electric vehicles, heat pumps, and the popularization of other consumer-based devices [6; 7]. In this scenario, energy system operators will have to be empowered with more advanced instruments to provide reliable electricity supply and quality of service (QoS) in the increasingly challenging energy system [8]. The goal is to allow the grid system to work as efficiently as possible, minimizing operating costs and environmental impacts while maximizing system stability and security [9]. Smart grids accomplish the required optimization of energy networks by the implementation of massive digitalization and other advanced technologies [10; 11]. They are necessary for the integration of growing amounts of variable renewable energy resources (RESs), such as solar and wind power, and of new loads, such as the charging of electric vehicles or bi-directional energy entities, such as energy storage units, while maintaining stability and efficiency of the system [12]. Furthermore, smart grids enable the exploitation of DERs to provide flexibility services that are potentially available or that will become available in the future [13]. To achieve the envisioned energy system with the aforementioned capabilities and functionalities, energy grids require a specific digital communication layer [14; 15]. Utilizing this layer, power devices, protection systems, and grid devices can communicate with each other and adopt the best configuration possible [4]. Several implementations have been performed in this sense, so far, using optical fiber [16] or the 4 th generation (4G) mobile networks [17; 18]. While the former is able to sustain requirements such as ultra-low latency, reliability, and availability of service (e.g., for demanding control and protection applications in smart grids), it also has high implementation costs and a lack of flexibility in case there is a need to connect a different power plant. In the latter case, 4G technology offers flexibility and scalability of the communication infrastructure. However, 4G has limitations in terms of the latency, speed, and reliability needed for the secure and reliable operation of smart grids. Fifth generation technology can be the proper solution by providing ultra-reliable connection, including slicing, together with speed and latency comparable to what optical fiber can offer, while having more flexibility in the installation [19]. Moreover, edge computing [20] can improve the ability of the grid to process information close to the power plants, which decreases the latency and need for bandwidth and increases the security.