Transmit beamforming for inter-operator spectrum sharing

In EU FP7 project SAPHYRE, we study the nonorthogonal spectrum sharing scenario, in which multiple operators are allowed to utilize the same frequency band in the same location and time. A major impairment in such a scenario is the interference that the cochannel transmissions create. Assuming that the transmitters are equipped with multiple antennas, we propose various transmit beamforming techniques to manage the interference. We show that efficient operating points can be reached, when the operators cooperatively design their beamforming vectors.