I. Introduction
Future wireless communication technologies are under development to adapt to different application scenarios of 5G and beyond (5G/B5G). Specifically, Enhanced Mobile Broadband (eMBB), Massive Machine-Type Communication (mMTC) and Ultra-Reliable Low-Latency Communication (URLLC), also called mission-critical communications, are widely considered the key services in 5G [1]. In other words, 5G networks are expected to accommodate a huge number of mobile devices with heterogeneous and stringent requirements in terms of data rate, latency, and reliability. To meet the heightened expectations for 5G, numerous wireless technologies have been developed including mmWave communications [2], massive MIMO [3], or ultra-densification [4]. However, capacity-enhancing solutions such as installing more cell sites (ultra-densification) or using additional spectrum (mmWave) are costly and may sometimes lead to underutilization of resources due to the time-varying network traffic. Thus, an alternative is to integrate a highly flexible communication platform that can be swiftly deployed to adapt to the dynamic traffic demand, yet ensure adequate quality of service (QoS).