Leakage-based multicast transmit beamforming

In this paper, we investigate downlink physical layer multicast transmit beamforming in wireless cellular networks, considering interference between multiple independent multicast transmitters (base stations). Transmit beamforming can exploit multiple antennas at the transmitter to direct the multicast signal towards the intended users, while minimizing the interference leakage caused to other users of the network. We propose a multicast beamformer optimization problem that maximizes the achievable multicast transmission rate while restricting the interference leakage caused to other users, by applying a semidefinite relaxation to approximate this NP-hard problem with a convex optimization problem that can be solved efficiently. Furthermore, we consider multiple receive antennas at the users and propose an antenna combiner that maximizes the achievable user rate. Finally, we combine the proposed beamforming and receive antenna combining methods via alternating optimization and evaluate the performance using Monte-Carlo simulations.