ed, but are rather 1 International Mobile Telecommunications-2020 (IMT-2020) is the codename used by International Telecommunications Union's Radiocommunication Sector (ITU-R) to describe the next generation of IMT technologies to be submitted to ITU-R and approved in a multi-year process of evaluations and consensus building scheduled to complete in the year 2020. The process, which started in 2015, aims at producing a new ITU-R Recommendation containing detailed specifications of IMT-2020 radio interfaces. 5G Radio Access Network Architecture: The Dark Side of 5G, First Edition. Edited by Sasha Sirotkin. © 2021 John Wiley & Sons Ltd. Published 2021 by John Wiley & Sons Ltd. 2 Market Drivers being developed in the hope that market need will "catch up" and eventually materialize to take advantage of these new technical advancements. In our view, unlike previous generations of cellular technologies, it is better to view 5G not as a single technology, but rather as a flexible system designed to serve many use cases and many markets. Such extreme flexibility comes at a cost of increased network and device complexity and, perhaps even more importantly, greater uncertainty of which features of 5G will be deployed and when. It is quite possible that different market forces in different geographies will drive the deployment of different features. It appears that in Asia the major driving force is the increased throughput for the MBB, while European operators are explor- ing various options for breaking into new markets (e.g. IoT), whereas in North America one of the key driving forces (at least for the moment) is fixed wireless access to provide better internet service to suburban areas. In summary, 5G may not be a one-size-fits-all technology as it is often presented, but rather a toolbox of different technologies that different operators (and potentially new entities) will use for different purposes. This is not new, as oftentimes this is historically how computing and networking technologies have been developed. A br