There has been a tremendous evolution from voice systems to sophisticated communication platforms in mobile communications. Today’s mobile communication systems provide various services and applications to millions of people. Future systems such as 5G are also expected to serve trillions of devices. It will neither today nor in the future be possible to predict the requirements of all use cases and applications. New business models will impose diverse set of requirements on future networks. A flexible radio network is required to deal with uncertainties and unknowns, and also to enable backward and forward compatibility.