Radio spectrum licences are generally specified in terms of the power a holder is allowed to transmit. However, if licences become flexible, allowing change of use and technology, then this licensing approach could result in significant interference between users. A new approach is proposed termed "spectrum usage rights" (SURs) which restricts the interference a licence holder is allowed to cause rather than the power they are allowed to transmit. This approach is shown to protect users against interference while providing the maximum flexibility possible and its implementation is discussed.
