I. Introduction

The fifth generation (5G) cellular networks are being rolled out across the world. 5G networks are shaping the industrial world as well as our daily lives, enabling many new applications, through multi-Gbps peak rates with ultra-low latency and ultra-high reliability [1]–[4]. However, public 5G networks, owned and operated by mobile network operators, also face important challenges for wide-spread adoption. Coverage is one of them. Mobile network operators tend to deploy networks in areas with large numbers of subscribers in pursuit of revenue to cover deployment costs. This may result in poor network coverage in less populated urban areas and an even no coverage in more remote zones. Coverage may also be unsatisfactory in indoor locations with harsh radio frequency (RF) conditions. Moreover, in a world where data breaches and cyber attacks frequently occur, high-technology industrial companies require the use of their own customized security policies and locally stored data, which may not be supported by some of the traditional public cellular networks. As a result of these shortcomings, private networks, which are also termed non-public networks in the 3rd Generation Partnership Project (3GPP) [5], have attracted significant interest.