## 1 Introduction  
The widespread rollout of fifth generation (5G) networks is not very far from becoming a reality [1, 2, 3, 4, 5, 6]. In such networks, there are three types of services whose requirements guide the technological evolution: massive machine type communications (mMTC), supporting millions of Internet of Things (IoT) devices with intermittent activity and transmission of small data packets [7], ultra-reliable and low-latency communications (URLLC), allowing zero-latency communication with high reliability, such as in critical and emergency applications as well as communications among connected vehicles [8], and enhanced mobile broadband (eMBB), accommodating traffic with high data rates, as well as cell-edge users' connectivity [9]. As the 5G era introduces various advantages towards providing ubiquitous coverage with high data rate availability, densification and high capillarity of access points are required to enhance 5G system capacity [10; 11; 12; 13]. In this context, a density of (even) thousands of nodes (drones or cars equipped with remote radio-head (RRH) or other 5G network modules) per square kilometer can be achieved, while in a traditional mobile network, there are usually not more than twenty base stations in the same area. A technical overview of the most significant challenges related to network densification can be found in [14]. To this end, the deployment of a large number of smallcells usually requires locations with costly backhaul and power facilities, which might hinder the mass deployment of smallcells. In addition, it should be highlighted that the deployment of \"parallel\" access networks would be very economically inefficient, especially in dense areas. Within future 5G infrastructures, network sharing should evolve beyond the traditional infrastructure sharing models used in previous generations, towards cloudification and virtualization. This is related to the need for multi-operator and neutral host shared infrastructure together with the higher network capillarity due to increasing number of users and particularly the exponential growth of connected things for IoT. Device manufacturers and vendors are already deploying 5G network equipment while mobile network operators (MNOs) are on the verge of commercializing 5G networks. MNOs have built their business almost entirely on public outdoor networks, offering access, connectivity, and managing large amounts of mobile data everywhere, supporting new services and content, while indoor (home and enterprise) services are covered with faster fixed lines (i.e., fiber optic) and Wi-Fi spots [15]. For this reason, many companies are interested in building their own 5G private networks (PNs), customized to optimally serve their specific use cases. To this end, a PN is a local area network that provides dedicated bandwidth using 5G technology. It can be deployed for a specific industrial application or for multiple industrial applications with diverse requirements. PNs are also referred to as non-public networks (NPNs) according to 3 GPP [16]. Although the concept of dedicated PNs for large enterprises or industries is not a new one, the advent of 5G networks provides plenty of new business opportunities for multiple actors [17]. Indeed, 5G PNs are expected to deliver high-speed, low-latency, and other 5G benefits, supporting next-generation applications. In this context, in [18], a technical overview of private 5G networks is provided, while spectrum opportunities and design challenges are discussed as well. In [19], a private mobile edge cloud was proposed to overcome the limitations of cloud-centered and edge computing systems. Based on the proposed framework, a number of bandwidth-demanding applications, such as pervasive video, virtual reality, and mobile video surveillance can be supported. In [20], a number of deployment options for NPNs in the industry 4.0, based on 3 GPP 5G specifications, is described.