The traditional way of handling spectrum for cellular wireless wide area networks and metropolitan area networks arose about 90 years ago based on the capabilities of radio transceivers and the regulatory requirements. Spectrum divided in chunks of certain bandwidth is exclusively licensed to operators by public auctions [4] for a decade or more duration. Furthermore, one radio access technology is assigned to the spectrum bands, e.g., global system for mobile communications, universal mobile telecommunications standard, long-term evolution (advanced), or high-speed packet access. Economists have long argued that market mechanisms should be applied to radio spectrum [20]. This trend to more flexible and market-oriented use of spectrum is supported by novel developments in radio technology, e.g., multiple antenna systems, multi-carrier techniques, and multi-user decoding. Following the development from intra-operator spectrum sharing to orthogonal interoperator spectrum sharing, the most promising yet most complex way of sharing spectrum is non-orthogonal inter-operator spectrum sharing in which several transmitters are active on the same frequency band and on the same time. On the physical layer, this leads to the classical interference channel model. Depending on the radio access technology and the transceiver structure, this type of sharing leads to a conflict situation between the transmitters (potentially belonging to different wireless network operators) because of interference on the same resource