s, see WRC-19 Provisional Final Acts (https://www.itu.int/pub/R-ACT-WRC.13-2019) 2 Market Drivers require much higher network densification compared with what is used today (i.e. massive deployment of small cells), which is also likely to affect RAN architecture and deployment considerations. There are also several challenges facing the implantation and development of 5G sys- tems with direct or indirect impact on radio interface design. These challenges generally fall under three categories. 1. How to protect various incumbent systems in potential future 5G bands. Various incumbents have varying technical and/or regulatory requirements for their protection. Addressing these requirements needs technical as well as regulatory solu- tions. 2. How to overcome propagation impairments, especially in higher frequency ranges. In mmWave, atmospheric effects such as rain and gaseous losses limit propagation and cell range. In addition, obstacle penetration is another limiting factor due to the fact that propagation by reflection and scattering are dominant in Wave as opposed to lower ranges where diffraction is the dominant propagation phenomenon. How to develop required antenna and RFIC technology in a cost-effective manner. Use of high-gain arrays and beam-forming is encouraged by the relatively small sized antenna elements in order to compensate for excessive path loss of mmWave. How- ever, designing cost-effective commercial components in such high frequencies is a new challenging area for the mobile industry. For instance, developing filter technology with sharp roll-off to curb unwanted emissions is more challenging in higher ranges than in traditional 3G/4G bands. In addition, mmWave have other system-related impacts as well. Certain deployment scenarios such as dense urban could present excessive multipath through reflection and scattering. In many cases, however, especially with highly directional antennas, a single reflected path is observed, followed by many smaller components. Antenna characteristics (beamwidt