rces must be properly dimen- sioned. Furthermore, as reliability planning (e.g. for mission-critical IoT applications) becomes important, mobile network operators may need to consider adopting four-tier reliability criteria developed by the Uptime Institute. Capital expenditure (CAPEX) and operational expenditure (OPEX) reduction are among the most important factors driving 5G RAN architecture redesign. In particular, tech- nologies such as virtualization and standardization of the fronthaul interface to create truly multi-vendor interoperable network interfaces are expected to drive down NG-RAN deployment and operational costs. However, in order to realize these benefits, operators may in fact need to invest more in CAPEX, taking upon themselves at least some integra- tion and testing efforts, in order to drive down OPEX in the future. Networks operating in the high frequency range (i.e. mmWave) require substantially more dense deployments, that is, a significantly higher number of remote units (RUs) (or Remote Radio Heads [RRHs]) or small cells. Additionally, availability and cost of fron- thaul transport network, along with transport network throughput and latency capabili- ties, will affect which NG-RAN architecture options an operator can deploy. Lower-level NG-RAN functional splits (see Section 4.5), while providing higher baseband pooling gains and better radio resource coordination, impose substantially higher transport net- work requirements and may not always be economically feasible to deploy, especially for the mmWave frequency range. Deployment Objectives and Challenges 7.3.1 Where to Provide Coverage In the past, operators primarily needed to provide coverage for human-operated terminals and user equipment. However, with the advent of 5G, millions of connected things will also require coverage. Predicting the origin of the traffic generated by humans was relatively 7 NG-RAN Deployment Considerations easy, as humans tend to concentrate in certain areas. On the other hand, predicting the origin of tra