Low Complexity Cooperative Multicast Beamforming in Heterogeneous Networks

This paper presents a low complexity sub-optimal algorithm for the max-min beamforming problem (MBP) in multicell multicast transmission in heterogeneous networks. The beam pattern is jointly optimized for all users inside a cell in a multicell scenario such that the signal-to-interference-plus-noise ratio (SINR) of the worst users is maximized subject to per-base station power constraints. The presented algorithm is based on an uplink-downlink duality framework derived by Lagrangian duality theory. The algorithm has similarities to a recent solution derived for the MBP with a unicast transmission. Compared to the standard semidefinite relaxation based bisection algorithm, the new approach is based on a linear program which is less complex compared to a semidefinite program.