Controlling spectrum use in a first wireless communications system which takes part in a spectrum assignment process, in which one of the first wireless communications system and a second wireless communications system assigns a portion of spectrum to the other of the first and second wireless communications system. The first wireless communications system includes a plurality of network elements some or all located within a cell associated with a particular network element of the second wireless communications system. The controlling includes coordinating network elements of the first wireless communications system to identify a portion of spectrum which is either available for assignment from the network elements of the first wireless communications system to the particular network element of the second wireless communications system, or required to be assigned from the particular network element of the second wireless communications system to the network elements of the first wireless communications system.