Beamforming in Underlay Cognitive Radio: Null-Shaping Constraints and Greedy User Selection
Source: Dresden University of Technology
In a multiuser cognitive radio setting, multiple secondary systems coexist with multiple primary systems. The authors assume the secondary systems consist of transmitter-receiver pairs, and each transmitter is equipped with multiple antennas while all receivers use a single antenna. In this setting, the secondary transmitters are to operate under the constraints of producing no interference at the primary users. Such constraints on the secondary systems are referred to as null-shaping constraints. Three results are derived in this paper.