Video now accounts for 71% of all mobile data and is heading for 80% by 2027, according to Ericsson among other sources, with an increasing proportion of that at ultra-high definition (UHD) and therefore demanding very consistent quality of service (QoS). This trend has spawned innovations at several levels to improve mobile quality of experience (QoE) within 5G itself, with streaming protocols, caching within the network, and overlays on the 5G infrastructure. Understanding each of these layers and how they interact is essential for enabling QoE that is good enough for UHD streaming. At the 5G level there are two aspects relevant for QoE, one being QoS flows within a single bearer, and the other network slicing, to hive off…