Multi-Group Multicast Beamforming in Cognitive Radio Networks Via Rank-Two Transmit Beamformed Alamouti Space-Time Coding
In this paper, the authors consider transmit design in Multiple-Input Single-Output (MISO) Multi-group Multicast (MM) Cognitive Radio (CR) systems. Previously, Semi-Definite Relaxation (SDR)-based transmit beamforming has been very successful in transmit design. However, recent research shows that further performance gain is possible by suitably modifying the transmit structure. Here, they propose a transmit beamformed Alamouti space-time code scheme for MM-CR systems, whose corresponding transmit design problem can be reformulated as a rank-2 constrained fractional semi-definite pro-gram. They then develop an SDR framework for this scheme and study its Signal-to-Interference-and-Noise Ratio (SINR) performance via both theoretical analysis and simulations.