main a problem for 5G as well. New business models centered around the neutral host idea may to some extent alleviate the problem; however, it remains a significant challenge that operators will have to find a way to overcome. Despite these challenges, there is a significant momentum behind 5G and there is no doubt that it will be deployed. Timing remains the biggest unknown. 2 Market Drivers Summary In this chapter we outlined the major market drivers behind 5G, ranging from technical requirements, to new spectrum, new deployment and business models, and deployment challenges. From these we attempted to derive how 5G technical requirements and business drivers affect RAN architecture design and deployment, and its evolution in 5G. In our view, the main factors impacting RAN architecture redesign in 5G are: Increased throughputs Reduced latency Network densification Competition. 4G is typically associated with throughputs of few hundreds of Mbps, whereas 5G is expected to deliver (at least in the mmWave bands) throughputs of many Gbps. Such a drastic increase in throughput affects not just the air interface design, but also the fron- thaul and backhaul transport network capabilities, and the RAN architecture. In particular, it is no longer reasonable to expect that even with fiber fronthaul transport, CPRI ² archi- tecture would be able to sustain such throughputs. This drives the desire to re-architect RAN in order to reduce fronthaul throughput requirements, for example, by moving more functionality closer to the edge. This is explained in detail in Chapter 4. Significant efforts have been made to reduce latency in 5G, which mainly focused on the air interface. However, for most mission-critical low-latency applications what is important is the overall end-to-end latency, and therefore air interface improvements alone cannot fulfill that requirement. In order to achieve actual end-to-end latency reduction, RAN archi- tecture changes are also required. For example, bringing the content closer to the edge (i.e. t