Interoperability is not just an issue for the RAN of course. In the emerging world of virtualized carrier networks, based on ETSI’s NFV (Network Functions Virtualization), operators are determined to avoid a new breed of vendor lock-in, and to deploy systems which support virtual network functions (VNFs) from multiple vendors, and which can interoperate at each layer. In addition, they need optimized interworking between the virtualized core or transport networks, and the virtual or physical 5G RAN, if their emerging new revenue streams are to be fully supported. NFV has emerged in a 4G world, but is expected to reach its full potential with the aid of 5G – because of the faster radios with their greater spread of use…