One of the key debates around 5G is whether it will be a clean break with past generations, or an evolutionary change, built on some elements which are already part of 4G. Most operators, weary of major migrations with uncertain ROI, favor the latter view, and believe that the parallel shift to IT-centric architectures such as virtualization and SDN will enable them to move in a gradual, as-required way towards 5G, with the software-driven platforms allowing old and new technologies to work together seamlessly. Telefonica is perhaps the best poster child for this approach. While other 5G frontrunners are heavily focused on getting to the newest technologies as quickly as possible, the Spanish group is running major trials, in parallel,…