Spectrum sharing is fundamental to 5G plans. Sometimes this is a way to open up a virgin band to multiple users, on an increasingly dynamic basis, in order to enable a far greater diversity of service providres in the 5G era, in line with the need to support many more industries and applications. Often it is a more defensive technology, aiming to extend the number of operators which can use an occupied band, while protecting the incumbent from interference – potentially a fairer, simpler and less politically contentious approach than pushing organizations out of prime cellular bands altogether. The most famous examples have been pioneered in the USA, especially the TV white spaces (TVWS) sharing scheme, which despite limited commercial…